undefined reference to `U2RXR' (art tech)

I am trying to reprogram some input port pins on PIC32MX450F256H, using MPLAB v8.92 I have reprogrammed the INT1 peripheral to work on RPD5:INT1R=0b0110; //RPORTD.5 //select port pin for INT1 input(works fine) When I try to set the port pin for U2RXR:U2RX..