Guitar Controller Xbox 360

How can I fix the green+red = yellow problem on the les paul guitar controller for the xbox 360 guitar hero 3?
When ever I hold the green and red buttons and strum down.. it also activates the yellow button on the game. but if i strum up it works fine.. I just hate doing that. Thanks for the help.
shove the guitar together becuase when u take it apart for sotrage the wires at the bottoms become less effective so kinda of just like jam it in
Guitar Hero 2 Glitches- 100% Glitch PS2 Xbox 360