I received this message from someone trying to build a map with some props I ported.

“Dear Horsey,
today I finally tried to use your props from witcher in hammer to create a map.
After compiling the map no prop is visible. Not even one out of the witcher props.
The error log from hammer says I have to compile the props via prop_static. Naturally I had done so all the time.
After searching on Google I found out, that the props itself may be are not correctly compiled.

Could you please have a look into the props out of witcher?”

I don’t know shit about hammer or what could be causing the problem.  Anybody have any ideas or suggestions I could pass along to the question asker?