I cannot imagine why .smi subtitles converted to (e.g.) .srt subtitles would not work. Did the conversion programme you used work properly? :?
You could also do the conversion from .smi to .srt using the easy program which I also use to sync (either .smi .srt and/or .sub format) subtitles, i.e. Vladimir's SubSync. Simply load the sami-file in SubSync and then immediately save it as a subrip .srt file (by changing the filetype into .srt upon saving).
See:
http://forum.bsplayer.org/viewtopic....f37285f6d#3489