Can not get event channel from the channel returned by Connect

[machelcheng]

Hi, i just meet a problem, I get event from channel returned by Connect failed.
my code is like this:

conn, session, err := zk.Connect(....)
go func() {
for {
event, ok := <-session
if !ok {
log.Errorf("fail to get session event")
os.Exit(-1)
}

When will I get event from session failed？