OK... I think I see what has happened.
There are two kinds of fittings that rely on compression...
This one uses a small band that is compressed at both ends...
This fitting is used very often in plumbing, for instance to provide a small tube to supply water for refrigerator's ice-making function.
I formerly thought that a compression fitting was a compression fitting, and I used this kind of fitting in some of my early refrigeration experiments. It turns out that this kind of fitting does not stand up to the vibration stresses and extreme temperature cycling that is the everyday life of refrigeration equipment. I know this because one of these fittings failed me and bathed the clothing I was wearing with spraying liquid propane. To say the least, it was unpleasant... to be more honest, I could have died.
Since that experience, I never even allowed the idea of the former type of compression fitting to enter my consideration as a valid type of alternative when working with refrigerant.
It may be possible to make this type work if the compression ring is brazed on (not soldered) to the tubing... maybe.
The other type of compression fitting is a flare fitting...
This type will stand up to the rigors of refrigeration, both to vibration and to extreme temperature cycling. It is commonly used in refrigeration work.
From the looks of things, I now think that Hv23t) has used the former type of compression fitting.
Not a good idea.
-AC