关于if语句求教

k:=0
for i:=1+k to image1.Width-1 do
begin
if (newbitmap.Canvas.Pixels[i,j-1]=0)and(newbitmap.Canvas.Pixels[i,j+1]=0)and
(newbitmap.Canvas.Pixels[i-1,j-1]=0)and(newbitmap.Canvas.Pixels[i-1,j+1]=0)and
(newbitmap.Canvas.Pixels[i+1,j-1]=0)and(newbitmap.Canvas.Pixels[i+1,j+1]=0)and
(newbitmap.Canvas.Pixels[i+1,j]=0)and(newbitmap.Canvas.Pixels[i-1,j]=0)then
memo2.Lines.Add(format('%d,%d',[i,j]));
k:=k+10;
怎么每次运行都不会运行这句啊:k:=k+10;
而且提示:value assigned to 'k'never used