The error you are getting means you are running the wrong file through AccuWage. Please make sure to run the W2 electronic submission file that was generated using W2 Mate trough AccuWage and not any other file. The path of the file generated using W2 Mate can be found under the “Output File” field inside the W2 Electronic Filing dialog.
Real Business Solutions Support Team, Makers of W2 Mate and Payroll Mate
708-479-8731