I think you need to draw the image three times: Imagine your background is \/

1.    \ [ /\ ] / \/
2.    \/[ \/ ] \/ 
3. \/ \ [ /\ ] /    

If you're seeing a black bar (I presuem you are clearing to Color.Black) you probably have an error in your positioning code.

I think you need to draw the image three times: Imagine your background is \/

1.      [ /\ ] \/ \/
2.    \ [ /\ ] / \/
3.    \/[ \/ ] \/ 
4. \/ \ [ /\ ] /    
5.      [ /\ ] \/ \/

(assuming Right ==> Left scrolling)

If you're seeing a black bar (I presuem you are clearing to Color.Black) you probably have an error in your positioning code.