.srt sometimes works.. sometimes doesn't

[jaxwire2003]

I have a Sigmatek XS-700 Pro standalone dvd player, which supports mpeg4 & srt subs.

About 50% of my movies don't show the subs, they appear fine when I play them in wmp.

Any hints on how to make sure that they will be shown on the standalone?

(yes the name is the same)

[jagabo]

Maybe the subs that don't work are in unicode to support non-english characters?

[handyguy]

Or your file name is too long....?

[jaxwire2003]

as far as I can tell the subs are in standard ansi. The filename is the same size as the ones that do work...