Your federal return was not accepted by the CRA - not filing for first time

When I use Netfile to submit my return to CRA's NETFILE service, I keep getting the following message:

 Message from CRA
"The Canada Revenue Agency was unable to process your return. Our records indicate you are not filing an income tax return for the first time with the Canada Revenue Agency. Please go back into your software and ensure you do not identify yourself as someone who is filing an income tax return for the first time and submit your tax return again. If you require assistance, please contact your software provider."

-I have been using Netfile for years and this is the first time I am seeing this message.

-I have verified that I am entering the NETFILE Access Code accurately.

-I have verified that I can log into my CRA account.

-How do I update the software to let CRA NETFILE know that I am NOT a first-time user??

-I really don't want to print and mail this in.

thx