please help, cant install opcode cache

Hello,
im having some issue with opcode : alternative PHP cache. i have contacted with my hosting they says opcode cache is working. i have posted on w3tc forum but no response. 🙁 i would really appreciate if someone could help me. of give me some guideline to get rid of this issue.

im running ubuntu 14.04 with apache. PHP Version 5.5.9-1ubuntu4.5
using digitalocean as hosting.

i have installed opcode successfully but still in w3tc it says not installed. therefor can choose only disk method for caching. all opcode options are grayed out.

from my info.php i can see opcode is running

Zend OPcache
Opcode Caching : Up and Running
Optimization: Enabled
Startup: OK
Shared memory model: mmap
Cache hits: 59075
Cache misses: 412
Used memory: 34051344
Free memory: 33057520

i contacted with my hosting they says its installed on server. cant understand where is the problem actually. after i googled i found opcode not run in php 5.5. so do i have to proceed with disk option only?

thanks again