From the sounds of this rejection message, you were attempting to submit a corrected claim to this payer and the claim control number that you entered is not valid.
When you create a corrected claim, Therabill asks you for the Control Number. The payer is rejecting stating that the control number you supplied is not valid (or they cannot match it to a claim in their system).
Why is a control number important?
When you submit a corrected (or a voided) claim, you must let the payer know what claim (that you previously submitted) this corrected (or voided) claim is replacing (or voiding). This is done through a control number assigned to your claims by the payer. You must use the exact control number assigned to your claim by the payer. You can usually get the control number from the Explanation of Benefits or Electronic Remittance Advice.
For information on how to created a corrected (or voided) claim, please see: Corrected and Voided claims in Therabill.