propane cannister problem leak

[jammie]

I had a new cannister of propane, bulk, it was put on and checked with the liquid and was fine. Then after a couple of days thought there was a smell when I finished torching so checked it tonight, there was a slight gas smell at the join between the regulator and the cannister so we checked it with the liquid and it bubble, we refitted it up, tight as anything  as usual, checked it again and there are still bubbles. have never had this before, anyone know whats wrong, I have also bled the pipes out , could it be a dodgy cannister, i tend to think it hasnt been right for a few days ad I hadn't really noticed  it  was def checked before the first use. 

[Dragonfire Glass]

try some PTFE tape on the thread 

[Helen G]

try some PTFE tape on the thread 

Exactly what I was gonna say

[jammie]

Thanks, am away to find out where to buy some !

[Dragonfire Glass]

B & Q, Focus, Wickes, any hardware shop