From the CRA rules:  

The transmitter CRA account number or RepID entered in the T619 electronic transmittal record must match the account number (MyBA or WAC) or Rep ID (RAC) used to sign in

The new rules are described here:  https://www.canada.ca/en/revenue-agency/services/e-services/filing-information-returns-electronicall...

Also, we have noticed that the BN must have 15 digits, I am not sure that this is a rule or not.