PHP Excel Error when entering SUM function to a cell

PHP Excel Error when entering SUM function to a cell

Please help with this issue i'm having when generating a EXCEL file with
sum formulas...
PHP code is like this:
$objPHPExcel->getActiveSheet()->setCellValue("I".$fila,"=SUMA(I17:I".($fila-1).")");
*SUMA is "sum" in spanish.. Works like that for spanish config
The excel when openning shows value as : ###### But the formula is
correct, when i just type enter after the formula it gets re-calculated
and correct.. any idea guys?? Thanks a lot