PML bundaries in HFSS

Hi all
I am trying to do a very simple experiment about the PML boundaries in HFSS. I define two boxes with PML boundaries. and I put a PEC sheet in between. This way All around my model is PML and in the middle I have a PEC sheet. then I define a plane wave as the excitation source. well, since the sheet is PEC I should get zero total field below that, but it is not zero. Can anyone please tell me where do these fields come from?! Do the PMLs in HFSS leak?

Thank you already
Kami