Access 2003 Small Coding Job

I have a small database that that I need some coding done on. I have a form for entering products into a table (tblMaterials) to record materials used on a porject. The form has 3 combo boxes on it but I can't get it to do the following 1st combo shows Supplier 2nd combo shows only Categorys that are associated with that supplier 3rd combo shows only products that are associated with the category in combo 2 and supplier in combo 1 The 3rd combo selection then populates a text box with units and a second text box with price. When I save the record all the entries must save to the tblMaterials On another form frmProducts I use this form to create new items in the tblProducts when I select a Category from the combo box it is not saving the selection to the tblProducts. The combo box selections need to come from the tblProducts