My model is not moving even after giving it a SetForce(0,1.00)

edit

My model is a simple mobile Robot taught in the tutorial. I am trying to make it move via plugin giving it parameters as in update function like

public: void Update(const common::UpdateInfo &)
{          std::cout<<"In update function"<<std::endl;
               physics::JointPtr MyJoint = _model->GetJoint("left_wheel_hinge");
                      if(MyJoint==NULL)
                          std::cout<<"My Left leg not working"<<std::endl;
               MyJoint->SetForce(0,1.00);
               std:: cout << "Joint Force : " << MyJoint->GetForce(0) << std::endl;
               physics::JointPtr MyJoint2=_model->GetJoint("right_wheel_hinge");
               MyJoint2->SetForce(0,1.00);
   }
};

i am confused plzz help fastt... thanks so much