The black plastic part (flat looking) on the top, looks to be pointing to the left to me. Mine is a little different. See if you can turn it to the right, to see it is is a lever. If it does move to the right, then put it back to the left. The green on the gauge below, is telling that both tanks are full. If it was red, that would mean the tank it is pointing to is empty, & the unit is pulling propane from the tank on the right. You can now, take the left tank and fill it up. You must have both valves on top of each tank turned on for the automatic transfer switch to work. Turn them on sloooowly for the the valve to work properly. Hopefully, all my info is correct. If wrong, somebody will chime in & correct my info. Good luck. Also fastest solution, if you are in campground, is go find a camper next to you and get some asap help.