SB_BOTTOM different from Win XP and Win98

[Benlecool]

Hello,

I'm calling this code:
RichEdit.Lines.Add(a);
RichEdit.perform(WM_VSCROLL, SB_BOTTOM, 0);
RichEdit.perform(WM_VSCROLL, SB_LINEUP, 0);

In Win XP it works fine, the last line is shown and it's in the bottom of the RichEdit. But in Win 98, the last line is show but put in the top of the RichEdit, so I can see only the last line.
Any solution?
Thanks.