include a file doesn't work for me .so

[Marko Pesikan]

Good day,
i had tried to  include a file with .*so *but it doesn't work. I get not 
the result what I wish.
It just represent the current code in the new document without drawing
What is wrong with my file schnitt.pic?
I would appreciated to get a hint?
regards, Marko

.
.
.H 1
.PS
*.so schnitt.pic*
.PE
.H 1.
.
.


$cat schnitt.pic
    ellipse "Arzt"
    move -0.2
    ellipse  "Patient"


I excute the file with:
mmroff test.mm  -mm -k -p  -Tps > test.ps && ps2pdf test.ps test.pdf && 
zathura test.pdf



GNU groff version 1.22.3