Hi Alexandra!
After looking into your site I have noticed that you link your buttons both by binding to dataset and customized link. Doing that cause the two methods to collide (one is a dynamic link and the other is pre-set to a certain item).
Moreover, I suggest you to divide the dynamic items by the field _ID instead of the field ‘Category’ (unless you’ve got a specific reason for that).
Please let me know if you need more help!
Doron. 