Error on changing time_reference to GMT?

[eluser]octavianmh[/eluser]
Hey guys,

So I'm working on this app that requires me to track and compute timezones, etc.. and basically have decided to convert everything that comes in to GMT and run it that way.. ANYWAY, when I changed the time_reference variable in the config file, all of a sudden i get:

A PHP Error was encountered

Severity: Warning

Message: mktime() [function.mktime]: 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 'America/New_York' for 'EST/-5.0/no DST' instead

Filename: libraries/Session.php

Line Number: 616

I've checked the code there, but am a bit afraid to edit the core libraries. Anyone seen this or know how I should proceed?

[eluser]octavianmh[/eluser]
Hmmm bump. No ideas? I'm running this locally, if that makes a difference?

[eluser]OliverHR[/eluser]
It is a php issue, what version are you using?

[eluser]octavianmh[/eluser]
My server is running 5.2.12.

Is that the problem?

[eluser]kimo_gusatava[/eluser]
yup me too!

I'm using zend server community edition...