Arduino, Xbee and Sparkfun shield issue

This is much geekier than my usual stuff (not that I post here much anymore.) Unless you’re good with Arduino and XBee this will not be interesting – and possibly seem like gibberish.

We have two Arduino Uno boards. Our board seem to transmit and receive each other, and we’ve tested the xbees – they work fine in an “echo” test we found that transmits from one and sends a signal back to the other. (Unwired).

As you can see in this video, we load up the two sketches (listed below) which we’ve simplified to be – one sketch sends an “A” character – the other, upon receiving any character, lights an LED. Very simple.

But even though the receiving board seems to be getting a signal from the transmitting board once a second, it does not trigger the rest of the sketch’s loop to run. If we wire the boards together without the xbees, the sketch runs. We are stumped.

Any advice is welcome.

int ledPin = 13;

void setup()
{
Serial.begin(9600);
pinMode(ledPin, OUTPUT);
delay(100);
while(!Serial.available());
}
void loop()
{
digitalWrite(ledPin, HIGH);
delay(100);
digitalWrite(ledPin, LOW);
delay(100);
}

transmit
//this is a program to see if the Xbees work
int ledPin = 13;

void setup()
{
pinMode (ledPin, OUTPUT);
Serial.begin(9600);
digitalWrite(ledPin, LOW);
}

void loop()

{
// delay(1000);
//digitalWrite(ledPin, LOW);
// delay(9000);
Serial.println(‘a’);
delay(1000);
//digitalWrite(ledPin, HIGH);
//while(1);
}