Frnds, i found it by myself. I had problem in node name. So i gave custom node name
[self addContentFromPODResourceFile: @"BlueBall.pod" withName:@"obj"];
CC3MeshNode* ball = (CC3MeshNode*)[self getNodeNamed: @"obj"];
Now it does work. So whenever we have a confusion in node name we can give by custom.