Most errors will be related to payment issues. looking up the reason details related to code will provide the info you need to correct the issue.

Many transactions fail due to Code 27, which is an AVS (Address Verification) mismatch. 

You can view the error codes in the Batch Processing details on the Accounting Menu. Simply click the link below to enter the last two digits of the error code to view the reason a transaction failed.

https://developer.authorize.net/api/reference/responseCodes.html?code=27

Example:

CODE: 27

EXPLANATION: The transaction has been declined because of an AVS mismatch. The address provided does not match billing address of cardholder.