Printing barcode labels with SAP ECC 5.0

Hello.

We are ugrading to SAP ECC 5.0 and using Zebra Z4M printer to print barcode labels. We have not modified our forms but in testing in the new environment, one of our labels prints the message 'INVALID - S'. The data is our material number which is numeric and 11 digits in length. If the number begins with leading zeroes, eg. 00591343801, the INVALID-S message is printed instead of the barcode. If the number is regular, ex. 59111111002, the barcode prints ok. The barcode label prints fine in our current SAP 4.6.

Has anyone seen this problem ? I appreciate any ideas or solution to this .

Thanks.

Van