Time Zone in AIX and cronjobs

Hi,

I am trying to change my Time Zone (TZ) variable in AIX 5.3
For that I have changed in /etc/environment
as TZ=GMT-1:30

although it is working but strangely none of my cronjobs are
executing at the correct time which were executing earlier
before TZ change.

Is a reboot necessary for changing TZ variable?
I have just exported the TZ variable in the .profile of root user

What could be wrong?
rte

cron daemon must be restarted after chaning the TZ.