update the calculation in array formula

[EddieChan]

I read the tutorial of array formula and have tried some example, I would like to know how why the array formula do not update the calculation automatically after I change parameter input ??

I need to click the cell that contain array formula and press F2 to enter edit mode and press "enter" for updating the calculation.

please advise if any setting I have missed ?? 

[#2]

@EddieChan sounds like your sheet might be set to manual calculate.  please make sure it is set to automatic.  Formulas -> Calculation Options -> Automatic

[#3]

@mtarler Million thanks, u r right ^_^