fix error

Hi
I want to simulate "scatterer on substrate" from a pdf I downloaded from site.
I did step by step from that toturial, but when I click "compute" it shows me the
following error

error in sweep: the following feature has encountered a problem
unknown function or operator
-name: mod1.ewfd.dst2scr_pc1
-feature: stationary solver1 (sol1/s1)
-error: unknown function or operator

It uses two periodic conditions in types of "Floquet periodicity" and I think this error
is related to this option.
please help me how can I fix it.