Infinite Elements - Electrostatics

Hi all,

I try to simulate an charged object inside an unbounded region. I use the AC/DC module --> Electrostatics in Version 4.1.
I attached the file. The outer bounds are ground and the charged 'cat' has a given charge density. The outer region is an infinite element.

When I start the simulation, I got the following message: Undefind value found.

Has anyone any idea, what I may make wrong? I try the same in Version 3.5a and there is no error.

Thanks a lot.

Best regards.
Irina Stockem