Your Google Ads must meet GTIN requirements
By May 16th 2016, all products assigned a GTIN must have it included in any Google Shopping ads that promote the product.
The Global Trade Item Number (GTIN) is used by a company to uniquely identify all of its trade items. Our Global Standards Partner, GS1, defines trade items as products or services that are priced, ordered or invoiced at any point in the supply chain.
Adding the product’s GTIN to a listing allows Google to easily match offers to the Google Shopping product catalogue, helping them to return the most accurate results to consumer using Google Shopping.
Enforcement begins on May 16th. Any listings that don’t meet the requirements will be disapproved and those that are not fully complete may not show within Google Shopping until the GTINs have been added.
See GS1 for more information.