It simply means the plug-in took too long to execute, perform an action and return the necessary information.
There is a simple rule that the plug-in must return something before the OGM finishes otherwise it times out. The simple solution is to make the OGM longer to ensure the plug-in always finishes returning before the OGM is complete. For example, instead of having just a blank OGM, perhaps play a message (eg One moment please while we process your request) or even 2-3 seconds of a blank audio file to give the plug-in a bit more time.