As far as I can tell, Panorama doesn't have such an error message. There are some error messages that say "does not exist". I'm sorry to be so pedantic, but to locate a problem it really helps to have an exact report.
Lookup isn't a statement. Which begs the question, what are you actually doing? I'm guessing that you are doing a formulafill with a lookup in the formula, since you've mentioned that in other posts. If that is the case, however, I cannot see how that error message could be generated from the formulafill statement.
Presumably you are doing all of this in a procedure. Does the procedure do anything else after the lookup is finished? Could the error be happening in the follow on code?
If you could possibly provide exact details of how to reproduce this problem, perhaps it can be addressed. At the moment, however, I don't see enough to diagnose the problem.