This is what Oracle has to say about this error:

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FRM-40502: ORACLE error: unable to read list of values.

Cause:  A fatal error occurred while trying to read a list of values.

Action:  Contact your DBA or an Oracle support representative.

Level:  >25

Type:  Error

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I had not encountered this error till recent times. But it was today I had encountered this error. I was scratching my head as to what caused this error.

I was working with a form with 6i release, converted to 10g. In that while clicking F9 for LOV in one of the fields, I encountered this error. I started debugging the form, starting from Field, LOV, Record Group. There were no problems at first sight.

I copied the SQL query from the record group and ran it in SQL*Plus, there was no problems. The query was using some bind variables from inside the form. I had modified these fields with values.

I then tried to run exactly the same where clause of the query (I commented out the bind variables) and ran the form. Bingo! It worked and the FRM-4502 error suddenly is gone.

I then tried to run the previous query (with bind variables), now also the error did not came.

I suppose this error is due to the ID of the field with which Forms works rather than the name.

It made a super note for me today...

Hope if you are in same mood, use this logic to solve your problem.

Regards
Anantha