[Y-Blockhead]

The fitting you have appears to be the new type fitting that comes with the gas lines that the vendors are selling. They have the ferrules connected to the fitting and (supposedly) break off when tightened. Yours is missing the ferrule.

IMO these new fitting/ferrules are junk and don't work anywhere near as well as the original type that have a separate fitting and ferrule. You really have to get them tight to break off the ferrule and crush the ferrule onto the gas line. I have seen numerous gas lines with the ferrule loose.

IF you can get ferules like Bob C shows that is the way to go.