Oracle Forms

Hello,

I've tryed to center a form using FORMS_MDI_WINDOW to retrieve the width and height of the parent window, but in 10g when i try it returns 0 for both values where is my code that I get from Oracle Forms Forum (here):


WHEN-WINDOW-ACTIVATED:

declare

mdi_ht number;
mdi_wd number;
frm_ht number;
frm_wd number;
xpos number;
ypos number;

begin

mdi_ht := get_window_property(forms_mdi_window, height);
mdi_wd := get_window_property(forms_mdi_window, width);
frm_ht := get_window_property('WND_MAIN', height)
frm_wd := get_window_proerty('WND_MAIN', width);
xpos := (mdi_wd - frm_wd)/2;
ypos := (mdi_ht - frm_ht)/2;

set_window_property('WND_MAIN', position, xpos, ypos);

end;

thanks for some help