Any idea why my WMP "Play To" function wont work for me?

Hi, I have both a Panasonic All8 and Jongo 3 Wireless Speaker in the house. I recently read about the "Play To" feature in WMP (from my Windows 7 laptop) to allow direct streaming to such devices. When I Right Click on a song and select "Play To", both speakers appear on the list of devices that comes up. However, neither will actually play! It all seems well up to the point of pressing...