even though full access privileges are checked in the program
Do you mean you've selected "run with full access privileges" at the bottom of the script editor?
In some cases "run with full access privileges" isn't really full access privileges. If the table your script is attempting to modify resides in an external file, this check box does not enable you to use full access privileges to modify it. It will still enforce the access privileges specified for this external file. This, I believe, is a security feature to keep someone from using this script option to modify data in a table to which they are not supposed to have access.
Does this sound like a possible explanation? If so, you'll need to trigger a script in the external file to what you need and set it to run with "full access privileges".