Maybe the following conditions are not met. When estimating the ratio of load Inertia to servo motor inertia, please satisfy the following conditions in order to ensure the correct ratio of load Inertia to servo motor inertia. 1) The accel. and decel. time for reaching 2000rpm should be 1sec. and below. 2) The rotation speed should be kept as 200rpm and above. 3) The load inertia cannot exceed 100-multiple of motor inertia. 4) The outside force cannot too much and the change of the ratio of load inertia to servo motor inertia cannot be excessive. 5) In AutoMode (when setting parameter P2-32 to 3 or 5), the system will stop to measure the load inertia value.