Hi ,
This is not a problem ; if you go to the Excel Options , under the Formulas section , you will find a checkbox which says :
Formulas which omit cells in a region
If this checkbox is checked , Excel will display this error for the formula ; if you uncheck the box , Excel will no longer display the error alert.
The error is being displayed because the region is from row 3 through row 18 , and the formulae are not referring to the entire region.
You will see that neither the first nor the last formula cell displays the error alert ; this is because for the first formula , reference is being made only to data in the first row , and Excel is unable to recognize whether the formula should refer to other rows of data.
For the last formula , it anyway refers to the entire region of data , and Excel considers this correct.
The formulae in-between do not refer to the entire region , and Excel thinks this may be a problem.
Narayan