when i press brake, rear lights go out/ no brake lights come on. Any suggestions ?

You have a short somewhere in the wirring from the brake switch to the tail lights and brake light ass. You will have to check the wirring for breaks. You will need a Digital Volmeter or at least a test light. Check the voltage back at the tail light ass for 12 volts at the bake light. Unplug one of the tail brake light ass and see if the short goes away `or gets better. Could be one of the tail light ass being bad and clean the bulb socket area so it is clean.