I have been using a baby booster for the last year with no problems but I connected it today & it just sits there doing nothing

.
I have 150 in the supply J & 150 bar in my cylinder (originally had 130 in cylinder) I have 250 bar in the drive gas cylinder. I have changed regs on the drive cylinder .yes I have made sure everything is turned on in the correct order :- J then my cylinder then the drive gas but still nothing .
Anybody else had this problem ? any ideas ?
__________________
Colin
I trust my rebreather completely ,
I just don't trust the user
onwards & downwards