Server uptime?

[rafaht]

Hi,
My server uptime is:
Server Uptime
Uptime: 0 days, 0 hours, 0 minutes 
Why isn't display the real uptime?
Is because I disabled some functions at php.ini:

Code:

pcntl_exec,pcntl_getpriority,pcntl_setpriority,system,shell_exec,exec,popen,proc_open,proc_terminate

?
If yes, how I enable this functions for Sentora only and disable for anoter websites/domains?
Thanks,

Edit:
In PHPSysInfo, this value is displayed correctly:
Uptime 1 days 1 hours 40 minutes
Last boot Wed, 11 Feb 2015 00:04:39 GMT