Excel 2010 Table - Formula column not editable?

Hi,

I have an Excel 2010 table which is generated by a data connection (to a Sharepoint table, but I wouldn't have thought that was relevant). I have inserted calculated columns in the table (the one in question has an IF function in it). As I understand it, I should be able to edit the formula in any cell and it updates the formula for the whole column. However, when I update the formula, only the one cell changes, and the formula is entered as text (i.e. no calculation!). Effectively therefore, I cannot edit the formula in the column. Does anyone have any suggestions as to how to edit the column...?

Format your cell as General - Select the Cell - Press F2 then enter - Also check calcs are set to automatic