Background to sprite : flickering

Hi,
I have a sprite working just fine but when I try adding a background I get problems.The code below is correct but when I add a background image it flickers and the sprite doesn't show.

Any suggestions ? Thanks in advance.

Graphics 1280,854 'set gfx mode
Global FrameTimer = MilliSecs()
Global frame:Int = 0

Global myimage:TImage = LoadAnimImage("ko1.png",32,32,0,240)


Repeat

Cls

DrawImage myimage,50,50,frame

If MilliSecs() > FrameTimer + 100
FrameTimer = MilliSecs()
frame:+1
EndIf

If frame >239 Then frame = 0

Flip
FlushMem

Until KeyHit(KEY_ESCAPE)