I think you are misunderstanding what nSprite does.
In your Blitz only version you are using DrawImage to put pixels onto the BackBuffer and then flipping it to the screen.
In the nSprite version you are using nS_DrawImage but only have a single sprite surface to draw to !!! So every call to nS_DrawImage overwrites the previous one. You will need to nS_CopyImage or nS_CreateImage to get more than one sprite (i.e. card) to play with.
... at least I think that is what is happening
In your Blitz only version you are using DrawImage to put pixels onto the BackBuffer and then flipping it to the screen.
In the nSprite version you are using nS_DrawImage but only have a single sprite surface to draw to !!! So every call to nS_DrawImage overwrites the previous one. You will need to nS_CopyImage or nS_CreateImage to get more than one sprite (i.e. card) to play with.
... at least I think that is what is happening