Speed brake

[Convoy]

Probably something silly, but I bound the speed brake in controls, but it does nothing. I don't see a speed brake extending. 

Am I missing something?

[Archer.xd]

Speedbrake is automatically retracted if >540kts airspeed (this also means you cannot extend it while above that speed) 
or if you have landing gear down,
or if you have centerline fuel tank loaded.

(ED MiG-29A manual pg57 last paragraph explains)

Edited 4 hours ago by Archer.xd
added manual ref

[Convoy]

2 minutes ago, Archer.xd said:

if you have centerline fuel tank loaded

That's it. Thank you!