MSP430FR2311: P2 IO IRQ not firing

Part Number:MSP430FR2311

Hello Everyone,

I am trying to write a simple edge detector using P2.2. The pin is connected to a by pass cap of another circuit t hat gets powered separately from the processor running this code. 

When I run the code and write to the P2IFG BIT2 in my main code I can force the IRS to run but when I power up the external circuit it does not run. I can see (via the debugger) the P2 bit2 change from low to high so why doesnt the ISR fire? 

Here is the initialization code..

void nfc_wakeup_init(void)
{
    // P2.2 is 2x input from nfc chip
    // should transition from zero to approx 3V when NFC powered
    // make input
    // make primary funciton GPIO
    // setup interrupt
    detected = false;
    P2SEL0  &= ~BIT2;
     P2SEL1  &= ~BIT2;
    P2DIR   &= ~BIT2;       // Set P2.2 to input direction
    //P2OUT   &= ~BIT2;       // set pull down
    //P2REN   |=  BIT2;       // P2.2 pull-up register enable
    P2IES   &= ~BIT2;       // P2.2 set from low to high transition
    P2IFG   &= ~BIT2;       // P2.2 IFG cleared
    P2IE    |=  BIT2;       // P2.2 interrupt enabled

}

here is the interrupt code

#pragma vector=PORT2_VECTOR
__interrupt void Port_2(void)
{
    //check IES bit
    if (0 == (P2IES | BIT2)) {  // low to high means nfc powered up
        P2IES |= BIT2 ;         // now watch for  high to low
        detected = true ;
        // start timer to poll for IAA
    }
    else {                     // high to low means nfc powered down
        P2IES &= ~BIT2;       //now watch for low to high
        detected = false;
        // stop timr isr
    }
    P2IFG &= ~BIT2;           // Clear P2.2 IFG
}

The main code just loops waiting for the detected var to change..

Any ideas would be  helpful, thanks for talking the time to look over my code..

Steve