Unacceptable quantity specified for this order. For reasons why, and help fixing this, see http://sellercentral.amazon.co.uk/gp/help/25341
This error occurs when the Quantity value in your tab-delimited shipping confirmation file or order fulfillment feed (XML) is incorrect. Common reasons why this might be the case include the following:
To resolve this error, please provide a positive Quantity value that equals the number of shipped items you have not previously confirmed.
You should not confirm shipment of the same items multiple times. Amazon considers all shipping confirmation or fulfillment data to be in addition to data previously provided. If your shipping confirmation file or order fulfillment feed contained errors, first remove the data for any records that did not contain errors before submitting your modified data a second time.