1702 The Contract Number is not associated to the Mailed on Behalf (...) [Solution]

When processing orders you might come across the "1702 The Contract Number {0} is not associated to the Mailed on Behalf of Customer Number in the CPC accounting system for the mailing date entered" error.

This happens when the Contract Number entered for the Billing Account on the Client level is incorrect.

Feel free to follow the step-by-step guide written below or the video guide, as you prefer:
 

To solve this issue you will have to:

1. Access Clients under the Maintenance menu
   
   
   
   
2. Click on the client related to the order
   
   
3. Edit the Billing Account related to the order and error
   
   
   
   
4. Select the Carrier Options tab
   
   
5. Verify that the information entered in the Contract ID fields is correct and matches with your registration information with the carrier
   
   
   
6. Press Save to apply the changes