A3 164 P615 CONTRACT ALPHA PREFIX IS REQUIRED :

Blue Cross Blue Shield uses what is called an alpha prefix on their primary ID (insured ID, subscriber ID).  This alpha prefix is what they use to route claims internally to the correct state office (e.g. Blue Cross Blue Shield of Illinois, Blue Cross Blue Shield of Michigan etc...).

This rejection from the payer is indicating that the prefix (assuming the alpha prefix) is not valid for the state.  Given that information, we might assume that the patient may have been issued a new insurance card, with a new primary ID (subscriber ID), with a new alpha prefix.

You may want to check with your patient to determine if they have new insurance.  Or, double check that you entered the primary ID (on the insurance card in Therabill) correctly.