Hi Mark - so it looks like the problem is that your curve is open and not a closed curve.

Note that when you select a closed curve, the type will actually read as "Closed crv" like shown here with a circle selected:



Since when your curve is selected it just says plain "Curve" as the type, that means it is an open curve, so there is a little space somewhere in it between the start of the first segment and the end of the last segment.

There is a plug-in you can install called "MarkOpenCurveStart" which will let you set up a keyboard shortcut that will create a point object at the start location of a curve - that can help you figure out which area to zoom in on to see where the opening is at. I guess Pilou is showing there that instead of a gap in that spot it's more like the sides cross over each other at that spot.

You can get MarkOpenCurveStart from here:
http://moi3d.com/forum/messages.php?webtag=MOI&msg=2888.11

- Michael