You have to assign an action or a function to the entities you create. If they don't need one, try:

ent_create("feld1.wmb", vector(0,-1024,-128), null);
ent_create("feld1.wmb", vector(0,1024,-128), null);
ent_create("wand1.wmb", vector(-992,0,64), null);
ent_create("wand1.wmb", vector(992,0,64), null);