[Shannon in ATL]

I just got a Weider Max 450, mainly for DH, but for myself as well. Tonight I did my second session with it. Sunday night I focused on arms and chest, tonight I did the exercises listed as for abs and back. Well, I could feel two of the ab exercises in my abs, but the ones listed for back felt more like shoulders and arms, the third ab exercise felt more in my arms. I know I did them right, I could have been tighter on the "tighten shoulder blades" part, but technically I think i followed the directions pretty well. IE, held arms straight, used the shoulders, abs, back to do the turning, arms were only holding the handles. That holding the handles while the cords pulled out is where I think I did something wrong...

Has anyone else used one of these types of machines and could give me a few pointers?

Thanks!