Here's visually what the others were referring to.
Problem: you have a sketch but no sketch filling presents (blue area). It is caused by the imperfection of your sketch.
Here's how to fix it step by step:
1) Draw a few crossing lines and you'll see where the sketch filling fails.
2) Where you see no filling, the control points are not overlapping. You have to connect them.
3) Zoom in and you'll see that some points are not connected, you just can't see it from far away.
+1) Once you connect the points (make them overlap), the sketch filling will be there.
The problem was most probably caused by you picking up the pencil and starting another spline (like when you move the canvas a little bit with your hand).
You thought you were starting exactly where you ended the last spline, but in fact you didn't.
Hope is helps. And again, as Istvan mentioned, you can do this tracing with much less control points.
If you upload the "Matt" picture itself here as a reply, I will do a short video on how to trace with far less points than you have. Less points will result in less human error.