Hi I would really apprechiate it if someone lets me know what I'm doing wrong to something that should be very simple.

I'm new to Maya and ive been stuggling with Maya's nurbs planar for some time now.
In the object below I am trying to close it so the object has sides and a closed top and bottom. My problem is that no matter what planar settings I tweak the model does not follow the curve accurately and so has horrible gaps on the edges.

Anyone got any ideas as to why its doing this? I've been scratching my head for days now wondering how something that should be so simple isnt capping the model right.