Issue with sorting in TMG

Hi,

I have a TMG and tcode for it.

I'm sorting the table based on material by adding code in PBO.

gt_table[] = extract[].

sort gt_table by matnr.

extract[]  = gt_table[].

Sorting works fine.

But, when I try to add new entry to the table, it all goes to display mode.

I tried using check before the sorting code. (if sy-ucomm <> 'NEWL').

But during save sy-ucomm goes initial.

Is there anyother way to sort?

Thanks in advance