Tango,
It's hard to troubleshoot this without being at your machine.
First off, what do you mean by "fire up the engines"? The engine start system in the Ka-50 is not automatic like the A-10C - it takes more than moving a throttle to start the engines.
Secondly, are you in Sim or Game mode? If in Game mode, it looks like the Throttle Up command isn't mapped by default. If in Sim mode, make sure you're making these key assignments in the "Ka-50 Sim" mode, not "Ka-50 Game". (see pic below)
Lastly, check to see if the same function is mapped to any other controller.