Can not install ZendOptimizer

[Phan Quoc Hien]

Hello,
I'm trying install ZendOptimizer with my php5 and get this error:

freebsd# make install clean
> ===>  ZendOptimizer-3.3.0.a cannot install: doesn't work with PHP version :
> 5 (Doesn't support PHP 5).
> *** Error code 1
>
> Stop in /usr/ports/devel/ZendOptimizer.
>
Why error? ZendOptimizer port is older?
Thanks.
-- 
Best regards,
Mr.Hien
E-mail: phanquochien at gmail.com
Website: www.mrhien.info