CGAL users discussion list

Hi all,
I am a new user of CGAL.
Now i have a question about the Halfedge.
I created a Voronor diagram in 2D from input points. And i want to draw all 
the edges. But when i use Edge_iterator to access the edges , i have problem 
with some edges that have either source or  target, but not both. I can get 
only one point and don't know how to get direction.

Can anybody help me? Thanks
greeting
Kuan