I am having similar problems to other postings. I created a letter to merge within Daylite and I keep getting the following message:
The merge failed, please ensure that all merge keys are derived from the template editor. During the merge for (conatct name). Error:

It doesn't tell me how to fix it either.

I also tried creating a letter in Word, and when I try to merge to THAT letter, Daylite crashes.

ALL HELP IS APPRECIATED!!!!!

What are some of the keys you're trying to use?

I recommend you send your logs in to Support (Help > Email log files) so that we can review the cause of the crash in your case.