MSP432 interruption gets stuck

The code below should to use interruptions to modify the time delay.

#include "msp.h"
#include <inttypes.h>

int i=0;                        
int T=50000;
int Tp;
int Ta;
int contador=0;

void main(){

    WDTCTL= WDTPW+WDTHOLD;
    P1SEL0 = 0x00;                                          
    P1SEL1= 0x00;

    P1DIR|= (BIT5);      

    P1DIR&=~BIT6;             
    P1REN|=BIT6;              

    P1OUT|=BIT5;

    P1IES  |= BIT6;                                          
    P1IFG  &=~BIT6;                                        
    P1IE   |= BIT6;                                         

    NVIC_ISER1 = 1 << ((INT_PORT1 - 16) & 31);              

    __enable_interrupt();                                


while(1){

	P1IE   |= BIT6;                                      
    if(contador == 0)
    {
        Tp=T/4;
        Ta=T-Tp;
    }

    if(contador == 1)
    {
        Tp=T/2;
        Ta=T-Tp;
    }

    if(contador == 2)
    {
        Tp=(3*T)/4;
        Ta=T-Tp;
    }

    if(contador == 3)
    {
        Tp=T;
        Ta=T-Tp;
    }

    if(contador == 4)
    {
        Tp=T/4;
        Ta=T-Tp;
        contador = -1;
    }


            P1OUT  |= (BIT5);             
            for(i=0;i<Tp;i++);
            P1OUT &= ~(BIT5);
            for(i=0;i<Ta;i++);
    //
}
}
void interrupcion( void )                            
{
	contador=contador+1;
	P1IFG &= ~ BIT6;
    P1IE  &= ~ BIT6;                                        
    P1IES &= ~ BIT6;

}

here is the start up file:

#include <stdint.h>

/* Forward declaration of the default fault handlers. */
static void resetISR(void);
static void nmiISR(void);
static void faultISR(void);
static void defaultISR(void);


/* External declaration for the reset handler that is to be called when the */
/* processor is started                                                     */
extern void _c_int00(void);


/* Linker variable that marks the top of the stack. */
extern unsigned long __STACK_END;


/* External declarations for the interrupt handlers used by the application. */
extern void interrupcion (void)
/* To be added by user */


/* Interrupt vector table.  Note that the proper constructs must be placed on this to  */
/* ensure that it ends up at physical address 0x0000.0000 or at the start of          */
/* the program if located at a start address other than 0.                            */
#pragma RETAIN(interruptVectors)
#pragma DATA_SECTION(interruptVectors, ".intvecs")
void (* const interruptVectors[])(void) =
{
    (void (*)(void))((uint32_t)&__STACK_END),

...

    defaultISR,                             /* DMA_INT2 ISR              */
    defaultISR,                             /* DMA_INT1 ISR              */
    defaultISR,                             /* DMA_INT0 ISR              */
    interrupcion,                           /* PORT1 ISR                 */
    defaultISR,                             /* PORT2 ISR                 */
    defaultISR,                             /* PORT3 ISR                 */
    defaultISR,                             /* PORT4 ISR                 */
...          

};

.....

The problem is that the interruption does not works, every time I push the interruption button, the output LED (p1.5)remains in the last state, it looks like the interruption gets stuck and does not return to the main code.

I am using CCS v6 in UBUNTU