Opcode cache: Not installed even after installing APC

Hello,
im using ubuntu 14.04 apache
i’ve installed APC for my server but from w3tc it says not installed. i cant use any cache methods for vertual server. all opcode options are grayed out. only disk is enable.
here what i get from my info.php file

Opcode Caching Up and Running
Optimization Enabled
Startup OK

can anybody tell me whats the issue? i really appreciate your help.

https://wordpress.org/plugins/w3-total-cache/