Subject: Why is there a space in the magnetic field around a bar magnet?

I was doing an experiment in science class with iron filings, a piece of paper 
and a bar magnet. I put a bar magnet underneath the piece of paper and 
sprinkled iron filings on top of the paper. The iron filings attracted to the 
bar magnet and created an outline view of the magnet. The iron filing that 
weren't near the bar magnet still attracted to it. However right around the 
edges of the bar magnet there weren't any iron filings. Why is this? 

Re: Why is there a space in the magnetic field around a bar magnet?