Prop_static/ Prop_Physics?

Whenever I place a custom ported prop into a map as a prop_static or prop_physics, it disappears, but I place it as a prop_dynamic, it works. Since dynamic props aren’t cheap when making a map, I was wondering if I have to place something into the .qc when compiling to be able to make it spawn as a static or physic prop.

I’ve found that if any prop has $propdata in the QC, it won’t work as a static prop, and if there isn’t any $propdata, it shouldn’t work as a physics prop. I haven’t quite figured it out, and I’m also probably wrong.

Okay, How would I use $propdata in the .qc, and how would I make a static prop?