Dlookup, Sub Sub Form

I have a Form, Sub Form and Sub Sub Form.  I am trying to use the DLookup function on an unbound control, OALUpperSpec, on the Sub Sub Form.  I want the event to trigger when a user clicks on any field located on the  Sub Form so that a number (decimal) appears in the Sub Sub Form's control named OALUpperSpec.

Q1: Where do I place the Dlookup code (form/subform/subsubform) and which event should I use to trigger?

Q2:  I have the following for the DLookUp function
OALUpperSpec = DLookup("[OALUpperSpec]", "t-Material, Spec", "MatlID="   [Need hep here])

[Need Help here] - MatlID is an integer and its also the field name used/present on the Form, Subform, and Sub Sub Form

Ken MilamEngineerAsked:
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Q1:  the sub sub form's Current event

If the MatID is in the subform's RecordSource, you can just refer to it there

OALUpperSpec = DLookup("[OALUpperSpec]", "t-Material, Spec", "MatlID=" & Me.MatlID)

If it is only in the parent, then

OALUpperSpec = DLookup("[OALUpperSpec]", "t-Material, Spec", "MatlID=" & Me.Parent.Parent.MatlID)

Or use a top-down reference to the parent form.

OALUpperSpec = DLookup("[OALUpperSpec]", "t-Material, Spec", "MatlID=" & Forms!frmParentForm!MatlID)

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