PIR going crazy with Xbee shield

Hey guys, just wondering why this is happening…
My PIR is working just fine while connected to the arduino, but when I insert an Xbee shield (haven’t configured it yet) it begins going crazy, detecting motion all the time.
I’ve made sure my pins are lined up properly.
Has anyone else experienced this before?
I’m attaching a photo and the code. again, this all works fine with just the arduino board.

int ledPin = 13; // choose the pin for the LED
int inputPin = 4; // choose the input pin (for PIR sensor)
int pirState = LOW; // we start, assuming no motion detected
int val = 0; // variable for reading the pin status

void setup() {
pinMode(ledPin, OUTPUT); // declare LED as output
pinMode(inputPin, INPUT); // declare sensor as input

Serial.begin(9600);
}

void loop(){
val = digitalRead(inputPin); // read input value
if (val == HIGH) { // check if the input is HIGH
digitalWrite(ledPin, HIGH); // turn LED ON
if (pirState == LOW) {
// we have just turned on
Serial.println("Motion detected!");
// We only want to print on the output change, not state
pirState = HIGH;
}
} else {
digitalWrite(ledPin, LOW); // turn LED OFF
if (pirState == HIGH){
// we have just turned of
Serial.println("Motion ended!");
// We only want to print on the output change, not state
pirState = LOW;
}
}
}

ps: I just noticed that my xbee is not properly placed, but that doesn’t matter yet because i havent configured it anyways. just checking why the sensor doesn’t respond well when the shield is placed.

Hello, Hope you have 3.3-V on the XBee. They will take a certain amount of abuse but anything over 3.6-V Vcc will kill it as will anything more on the inputs. You have got your XBee close to the PIR and although it's not a Pro version, it's going to chuck out RF at close range which might well be picked up by the PIR. Otherwise check the voltages going to the PIR when the XBee is powered up - check the Digi datasheet for the current used in transmit mode as it might be exceeding the limits of the Arduino or your shield - how are you powering the Arduino/XBee? Best to have a separate PSU and 3.3-V regulator for the XBee until you're sure. That's a hefty antenna on there and at close range it's going to give some powerful RF. What's the frequency? If you have a scope, see what's happening to voltages. Maybe add some decoupling caps. I have XBees on my bench powered up and don't have any problems but they all have their own supplies. Have you got Digi X-CTU new gen? Check what the XBee's doing. Even though you haven't configured it, there will be a default config on it. PIR's are essentially optical, but I had one as an occupancy detector in a cloakroom and the manufacturer issued a kit of suppressors etc. specifically to stop RF getting to the PIR and doing false positives.