Save Searches - [User's Category =Customer's Category] as Criteria ?

Hi,

Does anybody knows how to use Category [from User field list] = Category [from Customer field list] as a criteria in a Search List?

Scenery:

I have some Sellers that has Categories assigned within his User's Attributes.  Also I have a Category assigned to each Customer.

I need to create a save search to Show the Vendor only the Customers that Match his/her own Category.

I tried to use Use Expression but unfortunately I couldn't make it work.

Criteria => [User's Category =Customer's Category]

Thanks in advance.

Gustavo