How to sum data in one column based on the same month in another column using macros

A            B
2/10/2008    2
2/10/2008    3
4/10/2008    3
5/11/2008    4
5/11/2008    5

C            D
Oct/08       8
Nov/08       9

A         	B    	C	D     	E    	F
1   10/ 1/2008	24106	1	Oct-08	24106	8
2   10/31/2008	24106	7	Nov-08	24107	11
3   11/ 1/2008	24107	8	Dec-08	24108	6
4   11/30/2008	24107	3
5   12/ 1/2008	24108	2
6   12/ 2/2008	24108	4

B1 =MONTH(A1)+YEAR(A1)*12
E1 =MONTH(D1)+YEAR(D1)*12
F1 =SUMIF(B$1:B$6,CONCATENATE("=",E1),C$1:C$6)

=date(2008,small(month($A$1:$A$10),1),1)

=date(2008,small(month($A$1:$A$10),2),1)

=sum(if(month($C1)=month($A$1:$A$10),($B$1:$B$10),0))