Tom R,
If the male tube fitting went into the female adapter so far that the hex disappeared, it seems like something is not right, obviously. A thread sealant would be a thought, but this connection is suppose to be mechanical.
The male fitting should cinch around the tube and still have room to spare. If the tube were too small, this would account for it...but you purchased the tube assembly from a Bolt supply house as a unit.
Can you take the nut off and see WHY it isn't compressing. If it hasn't mashed around the copper tubing, it will come off, which it shouldn't do if it is fitting properly.
Mabye it's a new fangled style from China, and part of it is missing!
Stuart
