Parking lights.

I thought I had all the lights straigtened out. I finally got a pigtail for the parking light, 72 duster Sharktooth. the problem is now the parking lights will not come on with the headlights. With the headlights off, the turn signals work and the 4 way flashers will work in the parking lights in the grill. All other lights work. Where is the problem?
Thanks for any info,
T.J.