Update on FI-table BSEG

Hi,

i have an abap where i make a

update bseg set mansp = 'value' where cond..........

The update in bseg works well, BUT: the corresponding fields in BSID or BSAD are NOT updated. As bseg is a cluster-table i thought that the update in bsid and bsad will take place automaticly ???

How can i handle this ?