If you've loosened the nut before starting then it's not you it's the adaptor.

Obviously the nut that lock the valve closed has to be backed off before starting, but the rest depends on some dimensions. Gas station air chucks have a valve held closed by air pressure. Air will flow when the center is depressed by the stem in the tire valve. So easy that it's obvious, but the devil is in the details.

If your adapter is too tall, the tire valve stem won't reach the chucks and nothing will happen. If you look at a Shrader valve (which is what the chuck is designed around) you'll see that the stem is just slightly sub flush with the top of the valve. That's the critical dimension. Get it right and you're in (or the air is).