ConvertXtoDVD and smi. , sub. subtitle problem

I just got that program and I’m happy about it, but there’s still a little problem. It doesen’t support smi. and sub. formated subtitles. So I tried to change their formats with Subtitleworkshop and VobSub to srt. but nothing helped. Those srt. files I made, they even are not playing with KMP Player, but the original srt. files are.