Hm...there are only a handful of reasons I can fathom:
1. Sometimes, for some random reason, data erases in the CS even though you saved the file. It happens when you have too many topics in one quest, I've found. It only happens once in a while, and it only usually applies to scripts (this is all from my own experience). But, you might want to make sure that the data is still there or create another quest.
2. Maybe your topic id coincides with a vanilla topic id. Therefore, teh game is mixing them up. But that shouldn't happen, cuz the cs won't allow duplicates.
3. The only other thing I can think of is there's a small error in your topic as a whole. One little thing can mess it up.
Anyway, that's just my take.
Thanks,
Kroot