Try this...
noInterrupts();
EICRA = _BV(ISC11); //external interrupt 1 on falling edge
EIMSK = _BV(INT1); //enable external interrupt 1
EIFR = _BV(INTF1);
interrupts();
Try this...
noInterrupts();
EICRA = _BV(ISC11); //external interrupt 1 on falling edge
EIMSK = _BV(INT1); //enable external interrupt 1
EIFR = _BV(INTF1);
interrupts();