add entry to current line in table control

hi all,

i am working on module pool program.  how to add entry to current line of table control to ztable.

e.g:, i have ztable with 10 field, in that 5 fields already have value. And i created one screen with table contro wizard.

screen will display all fields with fields which have value in output only mode, remaining fields are in changable mode, now if i give value in remaining field and press save .

data as to store in ztable on the current line itself,  like this in ztable.

3961     2014     01     1006     2     6000     000     100     20     20     10     6000

but for me it is storing like new line. like this in ztable,

                                   1006     2     6000     000                                       6000

  3961     2014     01     1006     2     6000     000     100     20     20     10     6000

how to slove this.

regards,

S.Kavitha