Ggirl -
If you email me at "help@InstantTvChannel.com" I can probably help you out. Please include the problem stream URL. Without being able to test your stream, my best guess is that there's something amiss with the video encoding that is confusing the Roku device. Off the top of my head I cannot think of any settings in the Direct Publisher mode of Instant TV Channel that would keep the audio but drop out the video.
www.InstantTvChannel.com / www.InstantSubtitles.com - 717-441-4386 - Build a Roku SDK channel in 15 minutes! Easily and inexpensively generate subtitles!