Mandelbrot- What am I doning wrong?

@Indiepath.T
Yes, I think you'r right and yes I know. But what I do not know.

@Scott Shaver
Any ideas why that happens?

Here is the BB3D code

; Project: Mandelbrot - Speedtest
; Start: Tuesday, September 09, 2003
; Blitz3D - Linker Version 1.64


Global maxiter#=128 ; max iterations
SX# = -2.025 ; start value real
SY# = -1.125 ; start value imaginary
EX# = 0.6    ; End value real
EY# = 1.125  ; End value imaginary

x1# = 640    ; ScreenX
y1# = 480    ; ScreenY
xy# = x1# / y1#; x/y-ratio

   Graphics 640, 480, 16, 2
   xstart# = SX#
   ystart# = SY#
   xende# = EX#
   yende# = EY#

   xzoom# = (xende# - xstart#) / x1#
   yzoom# = (yende# - ystart#) / y1#
   fac#=0.999

  SetBuffer BackBuffer()
  While Not KeyDown(1)
      Cls
      xende# = xende#*fac#
      xstart#=xstart#*fac#
      ystart#=ystart#*fac#
      yende#=yende#*fac#
      xzoom# = (xende# - xstart#) / x1#
      yzoom# = (yende# - ystart#) / y1#
      mandelbrot(x1#, y1#, xstart#, ystart#, xzoom#, yzoom#)
      Locate 0,0
      thistime# = MilliSecs()
      Print "Speed: " + Str$(Int(x1#*y1# / (1+(thistime#-lasttime#)))) + " Kpix/sec"
      lasttime#=thistime#
      Flip
   Wend
End

; ------------------------------------------------------------- ;
; -=#  Mandelbrot  #=-
; ------------------------------------------------------------- ;
; calculate all points
Function mandelbrot(x1#, y1#, xstart#, ystart#, xzoom#, yzoom#)
; Local x, y, h, b, old, col
   LockBuffer BackBuffer()
   For x = 0 To x1#-1
      For y = 0 To y1#-1
         h# = DotsColor#(xstart# + xzoom# * x, ystart# + yzoom# * y) ; Color value
         If h# <> old#
            b# = 1.0 - h# * h# ; brightness
            col = HSBtoRGB(h#, 0.8, b#)
            old# = h#
         EndIf
         WritePixelFast x, y, col
      Next
   Next
   UnlockBuffer BackBuffer()
End Function


; ------------------------------------------------------------- ;
; -=#  DotsColor  #=-
; ------------------------------------------------------------- ;
; Color value from 0.0 To 1.0 by iterations
Function DotsColor#(xval#, yval#)
; Local r, i, j, m
   While (j# < maxiter#) And (m# < 4.0)
      j#=j#+1.0
      m# = r# * r# - i# * i#
      i# = 2.0 * r# * i# + yval#
      r# = m# + xval#
   Wend
   j# = j# / maxiter#
   Return j#
End Function

; ------------------------------------------------------------- ;
; -=#  RGB-Function - Come on, that's an important one...  #=-
; ------------------------------------------------------------- ;
Function RGB(red, green, blue)
   Return (red Shl 16) + (green Shl 8) + blue
End Function


; ------------------------------------------------------------- ;
; -=#  HSB2RGB  #=-
; ------------------------------------------------------------- ;
Function HSBtoRGB(hue#, saturation#, brightness#)
; Local red, green, blue, domainOffset // hue Mod 1/6

   If brightness# = 0 Then Return 0
   If saturation# = 0 Then Return RGB(Int(brightness#*255), Int(brightness#*255), Int(brightness#*255))

   ; Select not with <> allowed, have to use If here...
   If hue#  < 1.0/6.0
      ; red domain; green ascends
      domainOffset# = hue#
      red#   = brightness#
      blue#  = brightness# * (1.0 - saturation#)
      green# = blue# + (brightness# - blue#) * domainOffset# * 6
   Else
      If hue#  < 2.0/6.0
         ; yellow domain; red descends
         domainOffset# = hue# - 1.0/6.0
         green# = brightness#
         blue#  = brightness# * (1.0 - saturation#)
         red#   = green# - (brightness# - blue#) * domainOffset# * 6.0
      Else
         If hue#  < 3.0/6.0
            ; green domain; blue ascends
            domainOffset# = hue# - 2.0/6.0
            green# = brightness#
            red#   = brightness# * (1.0 - saturation#)
            blue#  = red# + (brightness# - red#) * domainOffset# * 6.0
         Else
            If hue#  < 4.0/6.0
               ; cyan domain; green descends
               domainOffset# = hue# - .5
               blue#  = brightness#
               red#   = brightness# * (1.0 - saturation#)
               green# = blue# - (brightness# - red#) * domainOffset# * 6.0
            Else
               If hue#  < 5.0/6.0
                  ; blue domain; red ascends
                  domainOffset# = hue# - 5.0/6.0
                  blue#  = brightness#
                  green# = brightness# * (1.0 - saturation#)
                  red#   = green# + (brightness# - green#) * domainOffset# * 6.0
               Else
                  ; magenta domain; blue descends
                  domainOffset# = hue# - 5.0/6.0
                  red#   = brightness#
                  green# = brightness# * (1.0 - saturation#)
                  blue#  = red# - (brightness# - green#) * domainOffset# * 6.0
               EndIf
            EndIf
         EndIf
      EndIf
   EndIf
   Return RGB(red# * 255.0, green# * 255.0, blue# * 255.0)
End Function

Sveinung