20 May 2011
match your form 16/16A with 26AS, and where the diff is found, visit the form 16/16A issuing authority and request them to revise their ETDS return, with correct data.
26AS is just acknowledgement of taxes deposited in any PAN, it can neither be applied nor rectified,
once respective ETDS returns are revised with correct data, it will appear in 26AS automatically.