Well, if ns_LoadAnimImage() works like the regular blitz LoadAnimImage (never used nSprite, myself), then I think you need to change this line:
to this:
Basically, I don't think your card image is getting loaded, due to the incorrect params.
card = nS_LoadAnimImage("cards.png",71,96,1,51)
to this:
card = nS_LoadAnimImage("cards.png",71,96,0,52)
Basically, I don't think your card image is getting loaded, due to the incorrect params.