Joker LPG tank valve not working - ideas?

[vanderkells]

Newbie here with recently acquired '89 T25 Joker.
No gas to hob/fridge. I disconnected regulator-looks like open/close valve not functioning.
Any ideas/solutions appreciated. (The tank was near empty so filled it up but still not working).

[California Dreamin]

Check all your valves are in the correct positions...the ones on the tank and those in the cupboard under the sink..note* the lower main valve under the sink goes inline with the pipe and is opposite to the others.

Martin