When changing bevel on curves, the curves disappear I'm currently trying to model a fox icon using Bezier Curves.
Here's what is looks like:



Or what I'm doing it by:


Unfortunately, I had some kinda weird goings on when I was filling it, or using
the "bevel" option. (Beveling, if you can say it that way)
As you can see in the first of the pix, most all of what I've done has been filled and thickened. But, when I try to bevel the curve that is highlighted (first picture), it simply disappears. I'm beveling it from 0 to 0.025, like all the others (which went fine).

The pic of the bevel value changed and the bezier curve gone:
For each point in a curve you can specify a radius, this value alters the radius of the bevel at that point of the curve. When a point has a radius of 0.0 there is no bevel at that point (or between two points of zero radius). While selected in object mode the curve is highlighted along the zero size area but deselecting it will hide that section.

Here we have a deselected curve with bevel.



Selecting the curve highlights an extra part that wasn't visible.



In edit mode you can see the radius value in the properties sidebar. You can also use AltS to adjust the radius in edit mode.