Dlookup after Copy Paste?

Question

Have a real quick question.

I am trying to figure out how to have my dlookup work if someone pastes to the field. If you enter the pack_number manually this works fine but if someone pastes multiple pack_numbers into column they won't populate.

I've tried to have it update afterupdate on the form as an event but it seems to lock the form. Any help would be greatly appreciated.

Code:

Private Sub Pack_Number_AfterUpdate()

Me.Refresh
        Me.Req_High_Retail = DLookup("[Current High Retail]", "InSHighRetailqry", "Pack_Number='" & Pack_Number & "'")

End Sub