PERL Module : Spreadsheet:WriteExcel

Hi,
I do not know if someone of you use this module to write excel files.
I've got a little problem to write some formula in the spreadsheet.
When I write a formula like : $excelWheet -> write
('A1','=sum(A2:C2'), this is ok
but if I write formula like $excelWheet -> write
('A1','=countif($C$3:$c$1000,"somthing")');
Then during the excution of the script I recieve an error saying that
line can not be parsed ...

Have you got an idea on how resolve this Problem ?
Thnaks a lot if you can help ...
Cheers,
Olivier