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.
de AD6WL ...-.-