When scrolled down

In table control when I have scrolled the mouse down, it continues to just before sy-ucomm.

For example when the user has wanted to add one more row to the table control, after added the row, She scrolls down and sees that more rows are created.

I have debugged it and saw that it holds the previous sy-ucomm(here add) and when scrolled adds rows.

I have cleared the sy-ucomm but this time other buttons are disabled some times, that is control is out of order.

What is the problem?

thanks.

Deniz.