70% of the time I cannot ignite the gas from gas arrow with flame wall

I am getting sick of having issues with gas arrow flame wall. I will put a flame wall directly in the center of the gas cloud with monsters in the cloud and it wont ignite until I cast another gas arrow through the wall of flame. I had to remove all but arcane tempo because those circles wouldn't ignite 90% of the time.

You need an ignite or detonator skill to ignite the gas, flame wall ignites stuff its not itself an ignite.

Flame wall is an ignite skill. I did this all during standard league. Have you read flame wall. Create a wall of fire in front of the character which ignites everything within it's area. This is having an issue this league.