Class.forName in plugin developement

[George]

Hello,
i am developing plug-in eclipse wich contains an wizard.This wizard lets the user to enter a class name with package name in current project and in treatment i need to do Class.forName("Class entred") but it dont work.Class Not found.
I think that the use of Class.forName in Plugin developement is not allowed.so how to do that?

Thinks for your help

[George]

it is impossible to do that!!!!!