AirPlay widget on iPad2 not present

The AirPlay widget does not consistently display in on my iPad2.

Here is a typical sequence of events: During my afternoon/evening commute I listen to a podcast in the car. When I get home I park the car, stop/pause the podcast and walk into my home.

At home, wi-fi is always on. The iPad detects and connects to my wi-fi network automatically. My A/V setup includes an Airport Extreme router along with a 2nd Gen AppleTV and 3 Airport Express units connected to remote speakers. All of this is built around a Mac mini connected to an HDTV.

When the iPad connects to the network it <i>should</i> also detect the AppleTV and Airport Express units. When it does--if the AirPlay widget present in the iPad's iPod app--I put iPad in its charging dock, use the AirPlay widget to select my bedroom speakers and I finish listening to the podcast as I get ready for yoga practice.

And there's the problem, sometimes AirPlay is available other times it is not. Restarting the iPad <i>always</i> fixes the problem but it is annoying. Does anyone have thoughts, insights on what's going on here?