What try aid is correct.
from what I can see your menus are passing the ID values for the brand and Class, but yur results table is showing the text for the brand and class.
For the search to work correctly, the column that the drop down list is comparing to must be the Foreign Key ID column
To populate the brand list initially, you must create a recordset to return all brands and make the the brand list dynamic using that recordset. Dynamic Dropdowns will over write the initial list with the correct brands for the selected class.