The headlight switch has TWO power feeds, B1 and B2. One is for only the headlights, the other for park, tail, and instrument. Be sure you have both power sources live.
Then check at the dimmer switch. Anytime the light switch is "full on," TWO of the dimmer switch terminals should be live. Be certain the hi beam indicator comes on when working the dimmer switch. It should be branched in, inside the car. Then go outside and be sure the headlights are GROUNDED, that the lamp sockets are wired to the correct pins, AND THAT THE lamps are actually "good."