Formula needed for countif or countifs (may also need a sumif)

Hi All

I was wondering if someone could help me with this formula. Basically at the moment I have this formula:
=COUNTIFS('Buyers List 2013'!R:R, "Africa", 'Buyers List 2013'!$L:$L, ">=1/1/2013", 'Buyers List 2013'!$L:$L, "<1/2/2013")

If date in column L is equal or greater than 1/1/2013 and less than 1/2/2013 count corresponding cells in column R that contain Africa.

I would like to keep this formula but instead of counting cells containing Africa, sum the volume in Column U for that row. Does this make sense and is it possible please?

=COUNTIFS('Buyers List 2013'!R:R, "Africa", 'Buyers List 2013'!$L:$L, ">=1/1/2013", 'Buyers List 2013'!$L:$L, "<1/2/2013")

To further explain I would like to sheet1 column a2 to equal the sum of all the volumes in cells in column U that correspond with Africa in cells in column R in between the dates of 1/1/2013 and 1/2/2013.

I hope this makes sense.

Cheers