[Inkscape-user] Difference operation between group of objects and single object

I have a rectangle, also a group of objects which is the result of creating a small circle and applying scatter extension so it distributes along the rectangle borders.

Then I try to apply the difference operation but doesn't seem to work. If I ungroup and I apply the operation selecting each circle and the rectangle one by one it works but not as a group.

Does Inscape allow to apply the difference operation between a group and a single object ? If it doesn't, some suggestions about how to do that faster ?

PD: I'm trying to achieve something like this: http://howto.nicubunu.ro/inkscape_postage_stamps/

Thanks in advance Guiu Rocafort