Queue Join Announcement

My free PBX server is setup and working, however i cant figure out how to have the join announcement for a queue only played if there are members logged into the queue.

Basically the join announcement welcomes the callers and tells them they will be next or what number they are, however if there are members logged in the call will be transferred to voice mail which at that point there is another message.

So the flow of this call is not right, basically i just need a way to skip the join announcement if there are no available members for the queue.

Any help is greatly appreciated.