image scale & screen res

Can't seem to copyrect to a texture,

tex = LoadTexture( "images/10296.png" )
aa=CreateSprite()
EntityTexture aa,tex

DrawImageRect font1,100,100,0,0,50,50
CopyRect 100,100,50,50,100,100,BackBuffer(),tex

this says can't find buffer, i.e. tex


or did you mean something else?