Cannot create class in system package while Using Sprite class

Hi i developed a game using Sprite class & imported

javax.microedition.lcdui.game.*; package. But when i tried to build this project it gave me "Cannot create class in system package" error. Worst thing is that now again if i build, then it displays error "package javax.microedition.lcdui.game.*; does not exist" . Pls help me

[344 byte] By [David_bourne5a] at [2007-10-3 4:18:11]