I think you'll need to be more specific...
White error messages?
Usually you see those if you changed the numbers of the dialogues (i.e. they do not exist) - please be very specific about how you are changing them.
Are you adding new entries, just changing text, which text editor are you using?
Also post a little picture in the game of an example dialogue that you changed and also post the old and new text and that should be quite a bit helpful in allowing us to aid you further...
Matt
/C\/C\
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