Calculating Torque but cant add Quaternion

Hey i know this gets asked alot but none of the answers help me solve my problem

im trying to sync the rotation on a ship in a mulitplayer game

my code is Quaternion VelocityToAddFromRotation = NetworkRotation - lastrot; Debug.Log(VelocityToAddFromPosition);

         Quaternion AngleVelocityToAdd = (NetworkAngleVelocity * 2) * VelocityToAddFromRotation;
         
         rigidbody.angularVelocity = Quaternion.Lerp(rigidbody.angularVelocity, AngleVelocityToAdd, 2f * Time.deltaTime);
         
         lastrot = transform.rotation;

this gets called when this ship is not there's

im getting an error on the line Quaternion VelocityToAddFromRotation = NetworkRotation - lastrot;

is wont lets me - the lastrot

Thanks ~Scott