Why H column not working???

All,

Its been awhile since I last posted. I need some help with this one. Please refer to the "Datasheet" tab.

I have columns that grabs the info from other tabs. At the bottom, starting at row 29, I have calculated the totals. Refer to column H. When adding up all the values in column H, the value is not correct. All other columns are adding up the SUMIF function properly but the H column isn't adding the values right. Please refer to M29 for the value of adding the 06L numbers in column H. Then when I copied all the data to the M column and then did the same calculation in cell H29 using the values from the M column...the values are correct. What gives?? Anyone help me to resolve this issue?

I may have found an error in Excel. Thanks for your info.

V/r,

Jason Noren