Compare with old lights to see if wiring different, when you say no main beam do you mean the inner and outer main or just one main, the earth gives huge problems on the connectors on the loom, but think you can get new connectors, trouble is the earth wire will be rotten inside the insulation.
On any I've done I've always run a seperate earth in addition, you could pull off the cap where you put in the inner main beam bulb and put a earth on there straight from battery to try.
Earth problems can be weird and wonderful, but easily fixed, did this on my mk1 sierra, xr4i and my dads xr4i all same problem.
tabetha