Hello Phan,
the red line is the Q-Factor of the received signal.
I am not sure what is your setup and I don’t understand the statement “My eye diagram is not the same as the eye analyzes”. If you can send the project layout as zip file, or change the extension to xxxx.txt and email it to ahmad.atieh@optiwave.com, I’ll take a look at it.
Regards,
Ahmad