Master Detail link was broken!! Help

I have an app. developed in delphi 3 c/s, with good working master/detail
relationship, and then I upgrade my database engine to 5.0 (from 3.x), I
found a strange problem, all the Chinese data became non-readable, but the
language driver is the same, so I created another set of tables with
different language, and import from the original table, now I can read the
Chinese again, but, another problem happened, the M/D relation DOES NOT work
either in design time or run time, could any one help me?
thank you !
David Ting