Welding Tips and Tricks

Hi everybody. I've purchased an oxy-propane cutting set up for use on the homestead- 18" weldgas torch and welders warehouse regulators + flashback arrestors.
This morning I put everything together intending to make my first attempt at gas cutting. Unfortuneatly I hit a snag before I could even light the torch- gas flows from the cylinders and into the regulators, and i can adjust the regulators, but no gas flows through the hoses to the torch. both oxygen and propane are getting no further than the regulators. I am using a 19kg propane cylinder and a 20l oxygen cylinder.
I am aware this probably sounds like a very naiive question, and I'm sure the solution is glaringly obvious to more experienced operators, so I appreciate any help you can give this dumb newbie. I'm very keen to get my torch working and start gaining experience of cutting, at the moment I feel like I've chucked my hard earned cash away on a white elephant.
Thanks in advance!

I've seen this happen before - check your flashback arrestors.

They have a direction arrow for flow and can be put on the wrong end of the hose.

Not only are the flash back arrestors directional - the hoses are in so far as they have " hose check " valves fitted ( in the UK @ least )to the torch end - if you try the pipes the other way round ( threads are the same both ends ) no gas will flow - visually never seen direction arrows but the torch end has a longer / bulkier fitting than the regulator end - obvious test is take off the hoses & flash backs & confirm you have gas flow from the regs - then check which part is wrong way round.

Also there are sometimes dust plugs inside fittings. Usually rubber or plastic.

Thanks for the help guys. I feel like a right buffoon, there were actually flow direction arrows on the hoses! In my defence they were pretty tiny.
unfortuneately I now have another issue- oxygen freeflows through the torch regardless of how tight i close the valve (on the torch, the regulator appears to function correctly.) Any thoughts? Is this me doing something wrong, or is it more likely to be a fault in the valve itself?