making a resistor in MOCMOS technology

Hello everybody, I wanted to know if there is a way to make a resistor
out of, for example, N-Active layer. It's not that I need a resistor,
it's just to extract its resistivity for an exercise.

What I did:

[Metal-1-N-Active-Con]  <------ N-Active layer conected to ------>
[Metal-1-N-Active-Con]

Then, exported both conectors as bidirectionals ports and last wrote a
spice deck from tool's menu. In electric messages' box I get:
"Back-annotated 0 Resistors and 0 Capacitors"
So here is my question, how do I can make a resistor out of any layer?

Thank you in advance!
Leandro