Mkv movies and subtitles

Hi there. The title speaks for itself. Basically, I downloaded some mkv movies with subtitles (I think they are hardsubbed, because there is no srt file: just video files) and the playbook can play the videos flawlessly, but it doesn't display subtitles. What could the problem be?

thanks in advance!

look into the app kalemsoft. i believe it has subtitle support.

I'll look it up, but it costs 6 dollars!

Ok. It works. Not flawlessly, but it works. Thanks a lot!