Plumbing question

[dba7108]

I have bought a 15mm to 10mm reducing valve for a radiator. When i tighten it up it clicks the goes loose. What am I doing wrong. The olive seems tight.

[Danns]

Without seeing it

Sounds cross (which would be rather tricky) or stripped thread to me.

Not that I ve ever had such happen to comment.

ETA - or it’s an oddly close match on the 15 and 10mm ends and you’ve got the 15mm nut on the 10mm end?