Referencing a Combo Box

Hi

How best to reference a combo box (CboGrn) from the parent form while in the sub form , I have tried this code below:

If (Me.CboGrn) <> Me.Parent!CboGrn.Clumn(1) Then
MsgBox " Please Check the selection is wrong try again"
Cancel = True
Exit Sub
End If
End Sub
I want to get the column 1 of the parent combo box , the code is on the form before update event, could it be this part Me.Parent!CboGrn.Clumn(1) is not correct. The error here is Me.Parent!CboGrn.Clumn(1) data part not found.

Are there any issues here to fix here??????

Regards

Chris