Dynamic Range within sumproduct formula

Hi,
I want to make the range in the following formula dynamic, so 2361
could be 3000,4000 etc....

=SUMPRODUCT((CUMPROP!$D$3:$D$2361=OFFSET($C6,1-$B6,-2))*(CUMPROP!$B$3:$B$2361='Summary Report'!$B6)*(CUMPROP!$G$3:$G$2361))


Should go something like this

SUMPRODUCT((CUMPROP!$D$3:$D$("&"A4" )=OFFSET($C6,1-$B6,-2))*........

where A4 denotes the last row of the range,
not quite working, many thanks