PHP 5.3.27 Installed; Plugin won't actibvate

Hello,

I have PHP 5.3.27 installed on my server but when I activate the plugin, I still get the message:

Plugin NOT active. This version of Quick Cache requires PHP v5.3+.

I confirmed with my host that PHP 5.3.27 is installed. We’re at a loss as to what’s up.

http://ww.wp.xz.cn/plugins/quick-cache/