INCORRECT GTIN

[bdavis4209]

I have an item with identical GTIN and UPC. I was told to replace the first two digits of the GTIN with 10 vs. 00 and use the 00 to start the UPC only. When I put in the GTIN as 10xxxxxxxxxxxx, the system tells me it's not valid. How do I move forward? 

[CommunityJedi22]

Hello and thank you for reaching out to us.  It sounds like you are running into an issue with your check digit (14th digit).  Please see below and let me know I you have any other questions.