General :: Can't Add Or Change Data

I finally found and eliminated all duplicate entries in my tblStoreProducts table, so that I could create a 2-field Index called UniqueProduct that would prevent duplicate entries. Without it, uploading information from Excel (not the preferred method) would result in duplicated entries in this table which would ultimately reflect in the Hazardous Materials reports that must be submitted to the fire marshal.

Today I was going through data entries in the Product table and noticed some that are STILL coming up with the UPC (a text field) in Scientific Notation.

I know that I have to change the information in the linked table tblStoreProducts first. The most simple way would be to just change the UPC of the product in that table to the correct UPC. It shouldn't be causing a problem, because it doesn't create a duplicate record. I'm getting the error "The text you entered isn't an item in the list" now that I've created that index.

I changed the index to Unique = No and still get the same error.

I removed the index all together...still get the same error.

I'm making the changes directly in the BE database right now. If I can't enter information directly, the forms aren't going to work either.