[MODULE] xBilling

[rafaht]

modpluz ,
I updated the settings of xBilling, but after I press the save button, I'll redirect to this link: ?module=xbilling&action=UpdateSettings and displays a blank page.
My Apache error log:

Code:

tail -f /var/log/apache2/error.log
[Wed Feb 11 11:55:02.168360 2015] [mpm_prefork:notice] [pid 11191] AH00171: Graceful restart requested, doing restart
[Wed Feb 11 11:55:02.330251 2015] [:notice] [pid 11191] mod_bw : Memory Allocated 0 bytes (each conf takes 48 bytes)
[Wed Feb 11 11:55:02.330279 2015] [:notice] [pid 11191] mod_bw : Version 0.92 - Initialized [0 Confs]
[Wed Feb 11 11:55:02.360998 2015] [mpm_prefork:notice] [pid 11191] AH00163: Apache/2.4.7 (Ubuntu) configured -- resuming normal operations
[Wed Feb 11 11:55:02.361026 2015] [core:notice] [pid 11191] AH00094: Command line: '/usr/sbin/apache2'
[Wed Feb 11 14:00:02.096487 2015] [mpm_prefork:notice] [pid 11191] AH00171: Graceful restart requested, doing restart
[Wed Feb 11 14:00:02.270934 2015] [:notice] [pid 11191] mod_bw : Memory Allocated 0 bytes (each conf takes 48 bytes)
[Wed Feb 11 14:00:02.270966 2015] [:notice] [pid 11191] mod_bw : Version 0.92 - Initialized [0 Confs]
[Wed Feb 11 14:00:02.339607 2015] [mpm_prefork:notice] [pid 11191] AH00163: Apache/2.4.7 (Ubuntu) configured -- resuming normal operations
[Wed Feb 11 14:00:02.339658 2015] [core:notice] [pid 11191] AH00094: Command line: '/usr/sbin/apache2'

I runned tail -f /var/log/apache2/error.log and try to change configurations now, but nothing has changed on the log...