EasyGerb follows a strict set of rules which your AutoCAD drawing must follow in order to get good quality gerber files.
1. To fill a boundary, it most be a "closed 0-width polyline" (not separate line segments like your drawing).
2. To make those triangles clear (i.e "islands") you will need to place them on a separate layer and output them as a composite Gerber file.
Please view our DXF to Gerber Guidelines for more assistance:
Note: If you do not want to follow the guidelines, we also offer a product called ACE 3000 which can join open boundaries, determine what's dark/clear (using De-Embed), and perform editing. If you're interested, we'd be happy to provide a movie tutorial showing how to convert your files using ACE 3000. Simply email us: firstname.lastname@example.org