Authorize.net Error During Transaction, Customer ID is required

The last week - we have been receiving an "Error During Transaction, Customer ID is required" on message when customers have tried to process their credit cards to make payments.  (We just announced this feature on our website so it's been very frustrating)

I've read through other threads on the forum and have tried what was suggested - getting a new transaction key from Authorize.net and deleting the old and adding a new Authorize.net payment field(s).  

It didn't work.  Any suggestions to fix this?

Simply set Customer ID as not required under your account.

To change the FIELD value (Customer ID) to NOT REQUIRED:

1.  Login to the Merchant Interface ( https://secure.authorize.net )
2.  Click on Settings and Profile -> Payment Form -> Form Fields
3.  Uncheck the Required box for the particular FIELD.