We just installed a hampton by track and bought Halo by Laser lights. Nothing is working. Are they not combatible? They are both "3-wire" systems, (I believe called "H" systems) with 2 wires on one side and one on the other.

I cannot say with any confidence that the Halo track heads are compatible with Hampton Bay track. I cannot find any detailed specifications for the HB track, since this junk is made exclusively for Home Depot by an off shore company.

I can tell you that :
Laser Track is only 9/16" (14mm) deep by 1 3/8" (35mm) wide.

And I attached a photo of the Halo Laser track, to help you determine if the heads will plug into the track. I really doubt it thou, since most manufacturers do not make their fixtures compatible with others, beyond the standards by NEMA and NEC.

Any if they did fit, for some reason, I doubt the assembly will be UL compliant, and would only be if either the Halo and Hampton Bay instructions state they are compatible. May be best that you get a matched set of track and heads, hopefully you choose Halo. And sleep easy that there will be no connection problems.