If you are receiving error like this:
WARNING: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for 'GMT/0.0/no DST' instead in line 457 of file plugins.inc.php
Its most likely timezone is not setup .
Open the config.inc.php in your AMS folder and at the top just below:
Add this line
if( ! ini_get('date.timezone') )
Save the file and upload back. The error should be gone.