Why aren’t my variations showing?

Google considers each variation it’s own product. In order for the feed to generate variations, it is required you set up a Variable Product.
From the Product setup page, select Variable Product from the drop down list.
Click the attributes tab and add any attributes you want.
Click the variations tab and “link variations”.
Your variations will be now shown in the data feed by generating a new data feed or by updating the feed list in Manage Feeds.