Closed Captioning

I'm using Cp6 and have created a cptx file and published it as an MP4 file.  The cptx file has Closed Captioning enabled and the CC check box is checked on each screen.  CC works great in the SWF file but when I publish the MP4 file to YouTube, I don't see the closed-caption icon in the YouTube video.

Am I missing something?

Thanks