BoxFill wrong params ?

Just check this code ?

I expect that BoxFill is  x,y,w,h
but he produce wrong position x,y  and also wrong size  
or i do something wrong ?



'test array fill RCB_315 by Aurel
win=0
i=0
Dim t$[1024] ' init string array
WindowOpen(0, "Fill_Array_by Aurel", WINDOWPOS_CENTERED, WINDOWPOS_CENTERED, 640, 480, WINDOW_VISIBLE, 1)
LoadFont (1,"FreeMono.ttf",20)
LoadFont (2,"FreeMono.ttf",16)
Font(1)
'open canvas
CanvasOpen(0, 640, 480, 0, 0, 640, 480, 0)
'set color
orange = RGB(255,220,0)
SetColor(orange)
'draw text
DrawText("Fill string array by Aurel",10,10)
update

cyan = RGB(200,220,250)
SetColor(cyan)
'draw text
Font(2)
DrawText("Init string array...",10,60)

'*************************
' how here add timer ?
'*************************
black = RGB(0,0,0)


For i = 1 to 1023
   t$[i] = str(i)
   'SetColor(black)
   'DrawText( t$[i],10,100)
   BoxFill( 100, 20, 10, 100)
   update
   SetColor(cyan)
   DrawText( t$[i],10,100)
   update
Next



While WindowExists(0) <> 0
update

wend