Please tell me :mega sensor shield v2.0 with xbee

I design a car when receive signal,car's xbee will send supersonic detect signal to computer terminal xbee

I define rx 15 pin and define tx 14 pin

but I connect tx?rx with any pin on board,the rx led when receive Signal by computer, even all bright !? and tx not bright

can any one please tell me

can you explain you probem more clearly please