Water won't boil??

Ok, all good responses. We have camped 700 feet above sea level and most recently, 5800 above sea level. We have tried both front burners independantly. At any altitude, same thing. We have tried to add salt to reduce the boiling point...same result. I also keep a two burner stove for boiling water. I will try adding a lid this week.

The flame is a bright blue.

So, in addition to the regulator from the tanks, there is a seperate valve for the stove/oven? Where would that be at, under the lid?

Thanks guys, lots of thinking to do now.