Negative index material in HFSS

Can you define a material to have negative ε and negative μ in HFSS? I tried but received an error as follows:

[error] Port refinement, process abc3d : subprocess "wave detected an incorrect value for permittivity, permeability, or the loss factors. (5:31 PM Sep 06, 2006)


Does anyone have experience doing this in HFSS?

Now, HFSS doesn't support the media with negative ε and negative μ

If this is true then how did this guy do it: http://www.emtalk.com/

Check out the figure showing negative ε and negative μ lens using HFSS.

After some tries, I was able to input negative index material properties (ε=-1 and μ=-1) in HFSS. I see that the normal component of H is in the opposite directions at the interface of the negative index material and the positive index material as it should be.