This is the same question you have posted before here:
http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=10439
isn't it?
I thought you have solved out the issue, if that's not the case you can post a reply to the other thread and it will be automatically re-openned.
If you still have the same issue, it would be helpful if you answered the following questions:
Would you please examine the generated queries in both cases (before and after the change), and manually run them directly against the database to see if the same problem occurs on the database side.
To get the generated query, please consult the manual's section "Using the generated code -> Troubleshooting and debugging"
Also please post the generated queries here. If you could not sort out the problem.