You might do better by increasing the number of pixels to about 500 or by saving as PNG or PCX (lossless formats) instead of JPG. I also got a poor result with the image that you posted above. This glyph should have only four contours, but because the black line is too thin, the image tracing interprets the line as broken.
With this image, I got a much better result. Try it and see. In my experience, bigger is nearly always better, so I use the upper end of the recommended range. If the outline is too big, you can always scale it down after generating it.
Otherwise, leave out the white bits, and add them back using Font Creators Hollow (Outline) Transforation.
See this Tutorial thread — Working With Transformations