Dt 2003

I have this problem with the electrics on my much beloved DT. it is the 2003 model and i am just no good with electrics. When i want the front light on dipped beem the back light wont work at all but when i put the light on parking the back light works but not the front! ive checked all bulbs and looked for loose wires but can anyone please help me out?!?!?!