Ray phase in ray tracing

Hello,

I'm trying to measure the phase of a bundle of rays that are reflected from an aspherical surface.
File 1 attached is the ray tracing and the red plane in file 2 is the surface on which I want to know the phase of the rays.
I can see that there is an option but every time I try to plot the phase on a curtain plane I recieve an error message:

Cannot evaluate expression.
Undefined variable.
- Variable: comp1.gop.Psi
- Geometry: geom1
- Domain: 3
Failed to evaluate expression.
- Expression: comp1.gop.Psi
- Plot: surf1 (Surface)

The 3rd domain is the aspherical surface that reflects the light (the circle in the files attached).
Any ideas of what is the reason?

Thank you!