MS access combo box

im building a small script for myself and have one problem:

in Access - i havemain form and a subform that include following fields:

Category (ComboBox) - Independant
Product (ComboBox) - Dependent
Price (textfield)
Total

I would like that when you select lets say category1 from Combo box - Category,
that in Product combo box only products that are under that category would be displayed.

I have write this code but i always get items from category1

SELECT DISTINCT ARTIKLI.ID, ARTIKLI.Name, FROM Products WHERE (((Products.IDKat)=[SubFormOrder]!IDKat)) ORDER BY Products.Name;

IDKat is the name/source of combobox 1 (Category (ComboBox)).

Thanks