is it a new mantle? if it is they need to be burnt before you use them. try putting a new mantle on and light with a lighter (no gas) mantle will smolder, once it has completely burnt it should be ok.
Most likely has a hole in it. Give it a good look over. They are very fragile once they have been used. Maybe it has come loose from the fitting too. They're only a couple of quid
check the air holes as well insects just love making houses in them if the lamp (or stove) is stored in a shed ,we even found a spider egg ball in our 3 way fridges chimney (about 3 inches up from the flame) which was difficult to diagnose then remove
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets