noise model issue

 Hello,

Would someone please explain to me this issue when I use different versions of the spectre APS simulator? I was using the pnoise analysis on circuit that contains hicum (bht) model, by MMSIM 12.1 vs 7.2.
The MMSIM12.1 result is pessimistic and contains noise sources called iciei1 and iciei2 in the printed noise summary, while MMSIM7.2 result contains sources called it and fn in the printed noise summary.
I also come across errors during pss-tran with the slower Spectre simulator on the hicum (bht) circuit, but I don't have trouble running the same on the APS engine.
My IC version is 6.1.5.500.9 (both 32 and 64 bit have been tried).

Thank you.
Fred