Games : i need help with /execute

I am trying to use the /execute and detect air below the player and set the block to a barrier block and the destroy it one second later. in doing this I am trying to make a double jump mechanism but a the moment the commands are in separate blocks using comparators and repeaters this is fine on single player but not multiplayer friendly. I did some research and I got this

/execute @e[type=Player] ~ ~ ~ detect ~ ~-2 ~ air 1 fill ~-2 ~-1 ~-2 ~1 ~-1 ~1 barrier destroy 0

but this dose not work and it comes up with

[11:52:19] Failed to execute 'detect' as mr_assley19

if any one could come up with any alternatives or how to fix the command that I've tried that would be great regards mr_assley19