Add On The Fly Does Not Work ..

I have exactly the same problem which seems to be caused by something to do with the server environment because my project uploaded to my Demo account works perfectly there.

So what to do?

There is not enough info to answer any of those questions. I recommend to contact support showing a way to reproduce the issue.

After the response 'tparki' I insisted on another server to test and to my surprise it worked perfectly. What could cause this problem.

note: Also does not work on localhost

Following help from Sergey <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=reply&id=70130&image=1&table=forumreplies' class='bbc_emoticon' alt=':P' /> I found that after invoking a table lookup for one of my fields I needed to ensure my user had ADD permission for that table. With that additional permission Add on the fly worked just fine.

Also managed to make it work.

Thanks for the support.