[NFS Most Wanted and Carbon] LB and RB not work when use for shift down and shift up

[Resdryn]

My control is generic that uses the X360 for Windows driver. And the LT/RT isn't a trigger, so I can't use them with the precision of the throttle joystick. Because of this, I decided to use the preset that I used on the PS2: Accelerate and brake on the RS, turn on the LS, nitro on the RB, handbrake on the LB, gear change on the RT and LT. However, I can't get this to work decently on the MW 2005 and the Carbon, after all the RT/LT is not recognized when pressed (but only when it is mapped for gear shifting).
; In-Game controls
GAMEACTION_GAS = XINPUT_GAMEPAD_RS_UP
GAMEACTION_BRAKE = XINPUT_GAMEPAD_RS_DOWN
GAMEACTION_STEERLEFT = XINPUT_GAMEPAD_LS_LEFT
GAMEACTION_STEERRIGHT = XINPUT_GAMEPAD_LS_RIGHT
GAMEACTION_TURNLEFT = XINPUT_GAMEPAD_LS_LEFT
GAMEACTION_TURNRIGHT = XINPUT_GAMEPAD_LS_RIGHT
GAMEACTION_HANDBRAKE = XINPUT_GAMEPAD_LB
GAMEACTION_NOS = XINPUT_GAMEPAD_RB
GAMEACTION_GAMEBREAKER = XINPUT_GAMEPAD_RSB
GAMEACTION_SHIFTUP = XINPUT_GAMEPAD_RT
GAMEACTION_SHIFTDOWN = XINPUT_GAMEPAD_LT
GAMEACTION_RESET = XINPUT_GAMEPAD_BACK
HUDACTION_PAUSEREQUEST = XINPUT_GAMEPAD_START
HUDACTION_ENGAGE_EVENT = XINPUT_GAMEPAD_DPAD_UP
HUDACTION_PAD_LEFT = XINPUT_GAMEPAD_DPAD_LEFT
HUDACTION_PAD_DOWN = XINPUT_GAMEPAD_DPAD_DOWN
HUDACTION_PAD_RIGHT = XINPUT_GAMEPAD_DPAD_RIGHT
HUDACTION_SKIPNIS = XINPUT_GAMEPAD_A
HUDACTION_NEXTSONG = XINPUT_GAMEPAD_RIGHT_THUMB
CAMERAACTION_CHANGE = XINPUT_GAMEPAD_Y
CAMERAACTION_LOOKBACK = XINPUT_GAMEPAD_X