Marketpress and W3TC total cache

I'm selling only digital products and for payment I use Paypal express.
Somebody is buying something and the orders were directly shipped.
Till now that worked very good. To improve my website speed, I installed W3TC total cache. Is working also very good. But... after installing W3TC the orders have the status of "paid" on not as "shipped" The result is that customers can not download directly what they have purchased.
Does somebody know what settings I have to use in W3TC.

Ella