Amplifier design with QuickSmith v 4.5

Hi
I need help to design an amplier with the free software quicksmith v4.5. The software don't work when I enter the S-parameters and click on stability.
Thanks in advance

Why not use other software? Say ADS, etc.

QuickSmith is freeware.

It seems a bit ancient, not updated for 2.5 years. Probably most people have never used this software, so you should try to contact the author.