Access - Click on record on Subform to Select Main Form Item

Hello All

I have a Form with one subform.  That subform is a continuous form where I list all Inventory Items in the system.  My main form is to input or edit an individual Inventory Item.

 (I didn't use a Listbox because I don't like the fact that I can't align individual list columns left, right or center - maybe you can and I just don't see a place to instruct it how to align)

So, on my Subform I have the primary key field [InvItemID] not visible.  They can see the [InvItem] description along with some other fields. In the [InvItem] OnClick event I want it to select the main form's selected Inv Item.

I tried using
Private Sub InvItem_Click()
    DoCmd.SearchForRecord , "frm_InvItem", acFirst, "[InvItem] = " & Str(Nz(Screen.ActiveControl, 0))
End Sub

However I get a Type Mismatch.