VBA for sumifs() with varying last row

I thought this would be possible but I get a "Compile Error" when entering the following code:

LastRow = Cells(Rows.Count, "DH").End(xlUp).Row
ActiveCell.Select
ActiveCell.Formula = _
"=SUMIFS($DG$4:$DG$" & LastRow & ",$A$4:$A$" & LastRow & ",""Unidentified*"", _
$DF$4:$DF$" & LastRow & ",""September 2011"")

I am attempting a sumifs() formula that has a varying last row.

Any help would be appreciated.

Thanks.