VBA code to copy formula down table

I got the following code from another poster, but it didn't seem to work properly, just made Excel crash:

Private Sub Worksheet_Change(ByVal Target As Range)
LR = Cells(Rows.Count, 1).End(xlUp).Row
PR = Cells(Rows.Count, 7).End(xlUp).Row
Range("G" & PR & ":I" & PR).Copy Range("G" & LR & ":I" & LR)
End Sub