Where does the problem occur on Performance Appraisal?

I have described in a previous answer the "ideal" flow of the appraisal process in steps ..

Problems may occur in any one of these steps when anthing in these steps goes wrong . Kindly refer to my previous answer on how  the ideal flow of the appraisal process goes ... and if you need further clarification, let me know !

Non-employee Rating approval and there is a dispute over the valuation between the employee and the direct manager