whats wrong with this linepick?

Blitz3D Forums/Blitz3D Programming/whats wrong with this linepick?

can you please see whats wrong with this. i suppose ive missed something really simple..
Graphics3D	 800,600,0,1
SetBuffer BackBuffer()

fl=CreateCube()
ScaleEntity fl,8,0.2,8

ball=CreateSphere()
EntityColor ball,255,0,0
EntityRadius ball,1

cam=CreateCamera()
EntityParent cam,ball
light=CreateLight()
PositionEntity light,0,10,0
TranslateEntity cam,5,10,5
PositionEntity fl,0,0,0
PositionEntity ball,0,2,0
PointEntity cam,ball
PointEntity light,ball

Repeat
	maxtilt#=18.0
	If KeyDown(203) And xx#>-maxtilt#
		xx#=xx#-1
		rollspeed#=0.01*-xx#
		bz#=-rollspeed#
	ElseIf KeyDown(205) And xx#<maxtilt#
		xx#=xx#+1
		rollspeed#=0.01*xx#
		bz#=rollspeed#
	ElseIf KeyDown(200) And zz#<maxtilt#
 		zz#=zz#+1
		rollspeed#=0.01*zz#
		bx#=-rollspeed#
	ElseIf KeyDown(208) And zz#>-maxtilt#
 		zz#=zz#-1
		rollspeed#=0.01*-zz#
		bx#=rollspeed#
	EndIf

	If xx#=0.0 Then bz#=0
	If zz#=0.0 Then bx#=0

	RotateEntity fl,xx#,0,zz#

	pick =LinePick (EntityX#(ball),EntityY#(ball),EntityZ#(ball),0,-20,0)
	PositionEntity ball,EntityX#(ball)+bx#,PickedY#()+1,EntityZ#(ball)+bz#

	UpdateWorld()
	RenderWorld()
	Text 10,10,EntityY#(ball)

	Flip
Until KeyHit(1)
End


EntityPickMode?
http://www.blitzmax.com/b3ddocs/command.php?name=EntityPickMode

doh. thanks :)