There are no revisions

Dear Support,

On our webshop the product are updated two oe more time a day. Its normal , from our store.
But we found, that there are no revisions for the products.
We found that there is a stackoverflow topic about this problem.
Can you please help us?
Here is the topic link:
http://wordpress.stackexchange.com/questions/65534/post-revisions-dont-save-or-show-up-only-for-custom-post-types/109782#109782