problem filleting a planar surface

 From:  Jonzker
2388.1 
im tryin to fillet the planar surface of this shape, it can be very small but still the program wont do the fillet,
link to the pic of the shape

http://img26.imageshack.us/img26/3456/questionfilletsl8.jpg

i included the file, ill apreciate any help with this

thanks guys!
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