Cannot get interrupts working

i have been trying create program awakens board low power state.  there lot written subject not implement because not interrupts work properly.
i tried copying , pasting simple blinking led light interrupt program on arduino site found not work either.
i wrote simple program triggers arduino go in , out of low power mode when button pushed. can arduino enter sleep mode can not awaken interrupt.

code: [select]


#include <keypad.h>
#include <avr/sleep.h>

const byte rows = 4; //four rows
const byte cols = 3; //three columns
char keys[rows][cols] = {
  {'1', '2', '3'},
  {'4', '5', '6'},
  {'7', '8', '9'},
  {'*', '0', '#'}
};
byte rowpins[rows] = {8, 7, 6, 5}; //connect row pinouts of keypad
byte colpins[cols] = {4, 3, 2}; //connect column pinouts of keypad

keypad keypad = keypad( makekeymap(keys), rowpins, colpins, rows, cols );




void setup() {
  serial.begin(9600);
  serial.println("start");
  pinmode(13, output);
  digitalwrite(13, low);
}

void blink_isr() {
  detachinterrupt(digitalpintointerrupt(2));
  sleep_disable();
}

void gotosleep() {
  serial.print("gotosleep");
  sleep_enable();
  attachinterrupt(digitalpintointerrupt(2), blink_isr, rising);
  set_sleep_mode(sleep_mode_pwr_down);
  digitalwrite(13, high);
  sleep_mode();
  /* wake here */
  sleep_disable();
  digitalwrite(13, low);
}

void loop() {
  char key = keypad.getkey();

  if (key == '#') {
      gotosleep();
  }

}




please post code here avoid need helping download it.

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