Graphics are not displaying in a php application

[rugwiza]

Hello,
I am running a vm centos 6.2 with cpanel.
recently,I migrated an application written in php,from a physical machine,but I encountered a problem:
-Some data were displayed in pie graphic, but now data are nolonger displaying. I tried to install php-gd, nothing changed. I also uncommented the extension=php_g d2.dll in php.ini, nothing changed. And I am sure, the development/DB part is very ok.
Anyone can advise?
thx

[Dormilich]

first question would be what dependencies those pie graphics have (GD is not the only image library available in PHP).