modify current ACS

which are the steps to modify current ACS ?

I should reset it (move origin to (0,0,0) and unrotate)

I have tried the following code, but the current acs is not modified :(

if (mdlACS_getCurrent  ( &origin,  &rotMatrix,  &type,  name,  description  ) == SUCCESS) {
                    moveElementsToOrigin(&origin, &rotMatrix);

                    origin.x = origin.y = origin.z = 0.0;
                    mdlRMatrix_getIdentity(&rotMatrix);

                    mdlACS_setCurrent  (&origin,  &rotMatrix, &type);  

                    mdlACS_saveNamed  ( name,   description  );
                }