Hi ZZZ, you answered your own question.  It definately needs a good ground.  That is the other half of your antenna.  It may tune up on 10 meters and should also tune up on 6 meters, but any other bands won't work without an adequate ground or if its a base setup radials will also work.  I have mine on my truck and it tunes fantastically on 40-6meters.  I don't use it for 2m/70cm.  I hope this helps.

73, Jim
de AD6WL ...-.-