Excel 2007 : If then formula issue

I am having trouble creating a formula that will return a blank cell (i.e "") if the sum of a string of other cells equals "0"...if the sum of those cells does not equal "0", then the actual sum should be the answer.

PHP Code: 

EX: cell H2=if(sum(H12:H15)="0","",(sum(H12:H15)) 


I have tried this formula, but it still shows a "0" value instead of a blank cell. If I take out the word "SUM" it brings back an error....grrrrrrr - I know there is a way to do this! Please help.

Why not just sum the cells in the usual way, and then use formatting to suppress display of zero? E.g.,

=SUM(H12:H15) and format as General;-General;