Update BSID

Hi all,

I need to do a direct update to table BSID for field zuonr, where i need to replace zuonr with a number.

I coded my logic this way :

select * from bsid into table t_bsid

where zuonr = <itb_bsid>-vbeln.

if sy-subrc = 0.

loop at t_bsid assigning <fs_bsid>.

<fs_bsid>-zuonr = <itb_s3>-zuonr.

endloop.

update bsid from table t_bsid.

if sy-subrc = 0.

commit work.

<itb_s3>-remarks = 'A'.

else.

<itb_s3>-remarks = 'C'.

endif.

- when i select * from bsid, my t_bseg is having the line of recod, and is manage to change the value for zuonr to the new value, but when it try to update bsid from table t_bsid, if return sy-subrc as '4'.

Can anyone help me on this? I'm in urgent to settle this, thanks alot!!