blend does not work on this object

 From:  wimverbe
8462.1 
for some reason, blend does not work here and I can't figure out why. I want a smooth transition on all edges of the hole in this object.

tnx for looking into this!

wim
Attachments:

Image Attachments:
Size: 86.9 KB, Downloaded: 10 times, Dimensions: 602x462px