intersection of curves in 3d doesn't work

hey,I;m trying to find the intersection point of for curves. when done on a 2d surface it works fine..however when I apply the same action to a 3d surface , it can't find the point..I get a list of 100 null items..this is really wierd because it looks to be intersecting when I review it in 3d space..why isn't it working?I use the action intersection/curve-curve.

I"m doing this on a diagrid surface..trying to find the intersection of the lines..or in other words the center for each subsurf...but that doesn't work well for what I need