Through the emulator? I've found the built-in proxy mechanism of Android emulators can be fickle at times.
Also, if you have the webtrends server address set to https, that will naturally make a difference.
I use Wireshark for debugging personally because it will attach to any network connection, even virtual ones to capture all in/out. I think that Fiddler looks for browser traffic specifically doesn't it? You still have https issues in Wireshark because you can't see the contents of the POST obviously but you still see that the traffic to Webtrends was sent.
I think some other folks here have advice on using proxy settings for the virtual devices and whatnot too. Maybe they can chime in.