This error is generated by Endicia when attempting to generate a USPS label. This error means that either the Account Number or Pass Phrase is incorrect.
First, keep in mind that the Account Number should not be confused with the User Name or ID that is used to login. This is a number issued by Endicia that identifies your account.
Second, the Pass Phrase is NOT the Password that is used to login to the Endicia site. If you are unsure of your Pass Phrase, go to this link:
Once the Account Number and Pass Phrase are correct you should not see this error. If you continue to get the error, contact support and we'll work with you to fix it.