Using a sumif with one criteria over a large range

All,

I have an excel formula that I cannot figure out. I have a large data set in excel 2010: About 15,000 rows and it has data on every column. The last column, IV, has the information in it that I would like summed. All of the other data are various dates (there are no identical dates in a row). The formula =SUMIF($N$7:$IV$14143,"9/1/12",$K$7:$K$14143) only gives me data from column N. I thought that I solved it using the following formula:

=SUM(IF(MMULT(($N$7:$IV$14143="9/1/12")+0,TRANSPOSE(COLUMN($N$7:$IV$14143)^0)),$K$7:$K$14143))

But this formula does not work on such a large data set. If you were to use the above formula on a smaller data series it works perfectly. Needless to say, I'm lost now. Any help would be greatly appreciated.

-MB32

That was my first response as well, but I was specifically asked not to use one...

After I comprise this data there are several more steps that others intend to do to the data and they do not feel comfortable with using a pivot table so it was a stipulation that no pivot tables be used.

I am not very familiar with how to use a sumproduct to solve this issue. Do you mind showing me an example formulat with based off the formula that I posted?

That would be of great assistance...

sumif.png

This would be a perfect example. The image is of a screenshot that mirrors my data, but my data is spread to the end of the column allotment (IV, where the numbers I want summed are). In this example my formula would work to sum for you the total associated with 9/1/12. But I need to find a way to mirror that result over a much larger data series.