Actuating joints with offline computed torque

Hi,

I would like to simulate a 2 link planar robot arm in SimMechanics. I used computer torque control method to control the arm in prescribed trajectory. The model runs fine in Simulink but having problem in SimMechanics. The system is getting unstable. But Coriolis and gravity terms are cancelled due to Computed torque law. I actuated my joints with a computed torque? Does it make any effect in joint actuation? But actuator block has the option to take torque as input. Is there any other issue to consider while converting to Simmechanics from identical simulink model?