Please let me know what is missing in this code....

Hi I don't need a new code to UART . But please let me know what is missing in the following code. I was testing it in proteus. I am at a very starting level in MSP430. Please help me...

#include "msp430f2491.h"
void uart_set();
int main( void )
{
  // Stop watchdog timer to prevent time out reset
  WDTCTL = WDTPW + WDTHOLD;
  uart_set();
  while(1)
  {
    UCA0TXBUF = 'A';
    while(!(IFG2 & UCA0TXIFG));
  return 0;
}
}
void uart_set()
{
   UCA0CTL1 = 0X71;// ACLK USED,ALL CHARACTERS RECEIVED
  P3SEL = 0X30; // P3.4 AND 3.5 USED FOR SPECIAL FUNCTION REGISTERS
  P3DIR = 0X10; // P3.4 TX GIVEN AS OUTPUT
  BCSCTL1 = 0XC0;//XT2 OFF, HIGH FREQUENCY MODE SELECTED, WITH 00 DIVIDER
  //BCSCTL2 = 0X00;//DCO FOR MCLK
  BCSCTL3 = 0X24;//3- to 16-MHz crystal or resonator WITH PF INTERNAL CAPACITANCE
  UCA0CTL0 =0;// parity disbled, lsb first, one stop bit, 8 character bits, uart mode with a software reset.
  UCA0BR0 =0XA0;// baud rate setting for 4MHz ,
  UCA0BR1= 0X01;
  UCA0MCTL =0X0D;//UC0BRX = 416,UCBRSX=6,UCBRFX =0 AS PER DATA SHEET
  UCA0CTL1 &=~0X01;//INITIALIZE UART
}