Excel 2010 AutoSum showing formula instead of results

I am experimenting with an excel 2010 report -- I created a pivot table then copied the results of the pivot table to another sheet in the same workbook.  All was going well, however, when I try to use autosum on column B - I clicked autosum and it put in the following formula:  =SUM(B3:B2441)  -- and the total shows up fine in the cell 2442; BUT -- I change the formula by changing the "B3" to "B4" since cell B3 has the year in the cell and that cell should not be included in my total.  Once I make the change, the formula then shows in the cell and not the results.  I did try to troubleshoot and find where someone suggested toggling between the formula and the results by hitting "Ctrl + `" -- but that did not work.  It is strange that the sum shows ok in the cell until I try to change the formula.  Any help would be appreciated.  Thanks