question on physics,,, what define a physics object?

i get errors. example: entity not a physics object in sphere:phent_set mass(my,5,ph_sphere)and etc.
i've try a mdl string, , wmp, wmb, i know its got to be something simple.can anyone define what make a physics object, or the correct setup for it.

thanks

phent_settype(my, ph_rigid, ph_sphere);

Add that at the top of your action, it enables the entity as a physics object.

thanks for the reply 2bit, after scratching my head for two hours i found the problem.the orginal file i had copy was incorrect or i had miss a pointer,, their example read like this.
ent_create(mdl_sphere,temp,sphere);
there was no pointer in the script for "sphere" the fix
ent_create(mdl_sphere,temp,my); or
ent_create(mdl_sphere,temp,null);

again thanks