Dash light won´t work, need help!

Hi all,

I have a tricky question: I own a ´68 Barracuda with rally dash. When I turn on parking light (switch position 1) the dash light is on, also the side markers. When I turn on low beam light (switch position 2) the dash light is off - also the side markers. Front lights work in both cases. High beam also works. Hopefully you understand what I mean, sorry for my poor english. Any ideas?

greetings Gerald