MSP430G2553 SPI master mode

I have a question about this code. I was trying to use the demo to setup an msp430g2553 as an spi master. But, I also added code so that the uC will wait until the button is pressed. I tried running the code, but it gets stuck waiting for the button press and nothing happens when I press the button.

Here is my code:

//SPI Master Test script

#include "msp430g2553.h"

unsigned char MST_Data, SLV_Data;

void main(void)
{
volatile unsigned int i;

WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
P1OUT &= ~BIT0 + ~BIT1 + ~BIT2 + ~BIT4 + ~BIT5 + ~BIT6; // P1 setup for LED & reset output
P1DIR |= BIT0 + BIT5 + BIT6; //
P1SEL = BIT1 + BIT2 + BIT4;
P1SEL2 = BIT1 + BIT2 + BIT4;

//code for button interrupt

P1DIR &= ~BIT3;
P1SEL &= ~BIT3; // Select Port 1 P1.3 (push button)
P1REN |= BIT3; // Enable Port P1.3 (push button) pull-up resistor
P1IE |= BIT3; // Port 1 Interrupt Enable P1.3 (push button)
P1IFG &= ~BIT3; // Clear interrupt flag

__bis_SR_register(LPM0_bits + GIE); // wait for button interrupt

UCA0CTL0 |= UCCKPL + UCMSB + UCMST + UCSYNC; // 3-pin, 8-bit SPI master
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 |= 0x02; // /2
UCA0BR1 = 0; //
UCA0MCTL = 0; // No modulation
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt
P1OUT |= BIT6;

P1OUT &= ~BIT5; // Now with SPI signals initialized,
P1OUT |= BIT5; // reset slave

__delay_cycles(75); // Wait for slave to initialize

MST_Data = 0x01; // Initialize data values
SLV_Data = 0x00;

UCA0TXBUF = MST_Data; // Transmit first character

__bis_SR_register(LPM0_bits + GIE); // CPU off, enable interrupts
}

// Test for valid RX and TX character
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR(void)
{
volatile unsigned int i;

while (!(IFG2 & UCA0TXIFG)); // USCI_A0 TX buffer ready?

if (UCA0RXBUF == SLV_Data) // Test for correct character RX'd
P1OUT |= BIT0; // If correct, light LED
else
P1OUT &= ~BIT0; // If incorrect, clear LED

MST_Data++; // Increment master value
SLV_Data++; // Increment expected slave value
UCA0TXBUF = MST_Data; // Send next value

__delay_cycles(50); // Add time between transmissions to
} // make sure slave can keep up

#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void) {

P1IFG &= ~0x08; // P1.3 Interrupt Flag cleared
_bic_SR_register_on_exit(LPM0_bits);
}