diff --git a/adf_loader/adf_loader_base.h b/adf_loader/adf_loader_base.h
index d8a6ba311..4d725d583 100644
--- a/adf_loader/adf_loader_base.h
+++ b/adf_loader/adf_loader_base.h
@@ -59,58 +59,61 @@ class ADFLoaderBase{
     ~ADFLoaderBase(){}
 
     // Load object attributes
-    virtual bool loadObjectAttribs(YAML::Node* a_node, std::string a_objName, afType a_objType, afBaseObjectAttributes* a_objAttribs){}
+    virtual bool loadObjectAttribs(YAML::Node* a_node, std::string a_objName, afType a_objType, afBaseObjectAttributes* a_objAttribs){return 0;}
 
     // Load Light Attributes
-    virtual bool loadLightAttribs(YAML::Node* a_node, afLightAttributes* attribs){}
+    virtual bool loadLightAttribs(YAML::Node* a_node, afLightAttributes* attribs){return 0;}
 
     // Load Camera Attributes
-    virtual bool loadCameraAttribs(YAML::Node* a_node, afCameraAttributes* attribs){}
+    virtual bool loadCameraAttribs(YAML::Node* a_node, afCameraAttributes* attribs){return 0;}
 
     // Load rigid body from a YAML::Node
-    virtual bool loadRigidBodyAttribs(YAML::Node* a_node, afRigidBodyAttributes* attribs){}
+    virtual bool loadRigidBodyAttribs(YAML::Node* a_node, afRigidBodyAttributes* attribs){return 0;}
 
     // Load soft body from a YAML::Node
-    virtual bool loadSoftBodyAttribs(YAML::Node* a_node, afSoftBodyAttributes* attribs){}
+    virtual bool loadSoftBodyAttribs(YAML::Node* a_node, afSoftBodyAttributes* attribs){return 0;}
 
     // Load ghost object from a YAML::Node
-    virtual bool loadGhostObjectAttribs(YAML::Node* a_node, afGhostObjectAttributes* attribs){}
+    virtual bool loadGhostObjectAttribs(YAML::Node* a_node, afGhostObjectAttributes* attribs){return 0;}
 
     // Load joint from a YAML::Node
-    virtual bool loadJointAttribs(YAML::Node* a_node, afJointAttributes* attribs){}
+    virtual bool loadJointAttribs(YAML::Node* a_node, afJointAttributes* attribs){return 0;}
 
     // Load joint from a YAML::Node
-    virtual bool loadRayTracerSensorAttribs(YAML::Node* a_node, afRayTracerSensorAttributes* attribs){}
+    virtual bool loadRayTracerSensorAttribs(YAML::Node* a_node, afRayTracerSensorAttributes* attribs){return 0;}
 
     // Load joint from a YAML::Node
-    virtual bool loadResistanceSensorAttribs(YAML::Node* a_node, afResistanceSensorAttributes* attribs){}
+    virtual bool loadResistanceSensorAttribs(YAML::Node* a_node, afResistanceSensorAttributes* attribs){return 0;}
 
     // Load actuator from a YAML::Node
-    virtual bool loadActuatorAttribs(YAML::Node* a_node, afActuatorAttributes* attribs){}
+    virtual bool loadActuatorAttribs(YAML::Node* a_node, afActuatorAttributes* attribs){return 0;}
 
     // Load actuator from a YAML::Node
-    virtual bool loadConstraintActuatorAttribs(YAML::Node* a_node, afConstraintActuatorAttributes* attribs){}
+    virtual bool loadConstraintActuatorAttribs(YAML::Node* a_node, afConstraintActuatorAttributes* attribs){return 0;}
 
     // Load sensor from a YAML::Node
-    virtual bool loadVehicleAttribs(YAML::Node* a_node, afVehicleAttributes* attribs){}
+    virtual bool loadVehicleAttribs(YAML::Node* a_node, afVehicleAttributes* attribs){return 0;}
+
+    // Load sensor from a YAML::Node
+    virtual bool loadVolumeAttribs(YAML::Node* a_node, afVolumeAttributes* attribs){return 0;}
 
     // Load Input Device Attributes
-    virtual bool loadInputDeviceAttribs(YAML::Node* a_node, afInputDeviceAttributes *attribs){}
+    virtual bool loadInputDeviceAttribs(YAML::Node* a_node, afInputDeviceAttributes *attribs){return 0;}
 
     // Load Simulated Device Attributes
-    virtual bool loadSimulatedDeviceAttribs(YAML::Node* a_node, afSimulatedDeviceAttribs *attribs){}
+    virtual bool loadSimulatedDeviceAttribs(YAML::Node* a_node, afSimulatedDeviceAttribs *attribs){return 0;}
 
     // Load all the TU device attributes
-    virtual bool loadTeleRoboticUnitsAttribs(string a_filepath, vector<afTeleRoboticUnitAttributes>* attribs, vector<int> dev_indexes){}
+    virtual bool loadTeleRoboticUnitsAttribs(string a_filepath, vector<afTeleRoboticUnitAttributes>* attribs, vector<int> dev_indexes){return 0;}
 
     // Load model from ADF file
-    virtual bool loadModelAttribs(string a_filepath, afModelAttributes* attribs){}
+    virtual bool loadModelAttribs(string a_filepath, afModelAttributes* attribs){return 0;}
 
     // Load world from ADF file
-    virtual bool loadWorldAttribs(string a_filepath, afWorldAttributes* attribs){}
+    virtual bool loadWorldAttribs(string a_filepath, afWorldAttributes* attribs){return 0;}
 
     // Load the launch file
-    virtual bool loadLaunchFileAttribs(string a_filepath, afLaunchAttributes* attribs){}
+    virtual bool loadLaunchFileAttribs(string a_filepath, afLaunchAttributes* attribs){return 0;}
 
     // Get the version of this loader
     virtual std::string getLoaderVersion();
diff --git a/ambf_framework/afPluginInterface.h b/ambf_framework/afPluginInterface.h
index 1771fd43d..1bbf3b8ea 100644
--- a/ambf_framework/afPluginInterface.h
+++ b/ambf_framework/afPluginInterface.h
@@ -230,7 +230,7 @@ class afSimulatorPlugin: public afPluginBase<afSimulatorPlugin>{
     virtual void graphicsUpdate(){}
     virtual void physicsUpdate(double dt){}
     virtual void reset(){}
-    virtual bool close(){}
+    virtual bool close(){return 0;}
 
 protected:
     afWorldPtr m_worldPtr;
@@ -254,7 +254,7 @@ class afWorldPlugin: public afPluginBase<afWorldPlugin>{
     virtual void graphicsUpdate(){}
     virtual void physicsUpdate(double dt){}
     virtual void reset(){}
-    virtual bool close(){}
+    virtual bool close(){return 0;}
 
 protected:
     afWorldPtr m_worldPtr;
@@ -277,7 +277,7 @@ class afModelPlugin: public afPluginBase<afModelPlugin>{
     virtual void graphicsUpdate(){}
     virtual void physicsUpdate(double dt){}
     virtual void reset(){}
-    virtual bool close(){}
+    virtual bool close(){return 0;}
 
 protected:
     afModelPtr m_modelPtr;
@@ -297,7 +297,7 @@ class afObjectPlugin: public afPluginBase<afObjectPlugin>{
     virtual void graphicsUpdate(){}
     virtual void physicsUpdate(double dt){}
     virtual void reset(){}
-    virtual bool close(){}
+    virtual bool close(){return 0;}
 
 protected:
     afBaseObjectPtr m_objectPtr;
diff --git a/ambf_framework/afPluginManager.cpp b/ambf_framework/afPluginManager.cpp
index 97ca8bc27..c5c762bcc 100644
--- a/ambf_framework/afPluginManager.cpp
+++ b/ambf_framework/afPluginManager.cpp
@@ -98,6 +98,7 @@ bool afSimulatorPluginManager::close(){
     for (vector<afSimulatorPlugin*>::iterator it = m_plugins.begin() ; it != m_plugins.end() ; ++it){
         (*it)->close();
     }
+    return true;
 }
 
 void ambf::afWorldPluginManager::init(const afWorldPtr a_afWorld, const afWorldAttribsPtr a_worldAttribs)
@@ -161,6 +162,7 @@ bool ambf::afWorldPluginManager::close()
     for (vector<afWorldPlugin*>::iterator it = m_plugins.begin() ; it != m_plugins.end() ; ++it){
         (*it)->close();
     }
+    return true;
 }
 
 void afModelPluginManager::init(const afModelPtr a_afModel, const afModelAttribsPtr a_modelAttribs)
@@ -207,10 +209,10 @@ void afModelPluginManager::reset()
 
 bool afModelPluginManager::close()
 {
-
     for (vector<afModelPlugin*>::iterator it = m_plugins.begin() ; it != m_plugins.end() ; ++it){
         (*it)->close();
     }
+    return true;
 }
 
 void afBaseObjectPluginManager::init(const afBaseObjectPtr a_afObjectPtr, afBaseObjectAttribsPtr a_objectAttribs)
@@ -246,4 +248,5 @@ bool afBaseObjectPluginManager::close()
     for (vector<afObjectPlugin*>::iterator it = m_plugins.begin() ; it != m_plugins.end() ; ++it){
         (*it)->close();
     }
+    return true;
 }