Error 18018

Adjustment request includes a negative value.

This error occurs when one of the refund components in an adjustments feed (XML) or tab-delimited adjustments file is a negative value. Refund components must be a positive value representing the refund amounts you wish applied to the order.

You cannot charge a customer's credit card by supplying a negative value.

To resolve this error resubmit your adjustment data with positive refund values.