excel can not be cited another excel file data

For example:in a document written consensus = A15 + other documents B15, but B15 is clicking, A formula did not file any response, please help explain why? How to solve? Re-install the software too.

You have to write A document on “= A15 +”, and then again at the other documents the two documents B15 is not a document Name, if a file name a few subfolders for example, you can SHEET1 enter the C3 formula, the formula is how it should be = A15 + SHEET2! B15.Tool you choose, the option to re-calculate, calculate the stack again and again Mody, a look at the next election.
You look at Gerry is a unit under the non-numerical format.
Above are not the problem, but also on the same computer, there are two, excel are their own problem .
my computer also appeared in a form, a cell from playing the number one hit on a number of Death, playing a number of other no problem, there is no other form of such a problem , Censored form, a new workbook and then we can not.