Non-Supported format detected

Hi, I recently bought a Philips GoGear SA6185 portable media player, which came bundled with Media Converter for Philips v2.0.2.75. When I connect my media player it is recognized under select device tab, and when I convert video files to current device everything works fine, the problem is that when I try to play the converted file on the GoGear I get a message "Non-supported format detected. Use the Philips Media Converter converter to convert files to the device." Like I say, I used the converter to do this but the files won't play. I have also tried converting to folder and syncing the file to my player with media player 11, but still no joy. The pre loaded video that came on the player works fine