if condition calculate sum...

I'm trying to explain my problem as simply as possible (I'm not too good at explaining :P)

I have A1:A6, each cell contains a date (1.5.2010 - 6.5.2010) and B1:B6 with numerical values.

C5 contains the date 5.5.2010

I want to find a way to compare C5 to A1:A6 and IF the value from C5 is found in A1:A6, calculate the sum of the corresponding cells in column B and paste the result in D5.

basically, in the above example, D5 shoul be B1+B2+B3+B4+B5 because 5.5.2010 is found in A5.

any ideas how this can be done in excel?

I have excel 2010 beta and the dates are in dd.mm.yyyy format

If the dates are real dates you can use SUMIF like this

=SUMIF(A1:A6,"<="&C5,B1:B6)

except for ";" instead of "," it works flawlessly! Thanks a million! tried to find a solution for hours and hours, and you solved it for me in minutes.