Convert to symbol - fill disappears!

I got 2 layers on the timeline, the first layer is filled with roads* (just a white shape with black stroke)*, and the other layer is just a rectangle acting like a background.

After I convert these 2 layers to a MovieClip, the filling in one place just disappears!
http://pasteboard.co/y8KptmB.png *(The red part is the stage’s background color)
*
Any tips how to avoid this, would be very appreciated!
~Tompa