In my WP7 app, I was able to display the placeholder ad using ApplicationID="test_client" and AdUnitId="Image480_80". This worked in both the emulator, and on the phone.
I have set up a single application and one ad unit in Pub Center, but when I use the ids from these, the advertisement doesn't appear in either the emulator, or on my phone. I see a quick white border appear, and then it goes black.
I haven't published my ap to the Application Center and wanted to verify that my trial mode (with advertising) will function correctly.
Thanks in advance,