No power to slide outs

I know all slide out are operated differently. Mine are Power gear and to operate, parking brake set, gear shift in Park, motor running and then you can slide away. Dose your owners manual give instructions? ~If not what brand of slides do you have? Also give the directions you are using to try to operate your slide. Might help someone else trouble shoot. The reason power gear recommends having the motor running is then the alternator is putting at least 13.8 to 14.1 volts back into the battery while you are operating the slide. I know there will those that say they do not run their engine and if your manual says not to, then do what your manual says.