I think you need to provide us with more details.
"contact your vendor" does not sound like a standard Microsoft Access error code.
It sounds like specific functionality programmed into the database.
If you do not feel you can sufficiently explain the structure of the database, and explain exactly what you are doing when you get this message (and then let us know what your expected results are), you may want to upload a copy of the database for us to analyze. Just be sure to remove any sensitive information from it first.