MSP430F5528 - Clock and UART

 Hello, I'm trying to communicate with my RF module through UART interface. However, I get many errors even with low load. I suspect that I have an issue with the way that I configure the clock or the UART.
 

 Basically, for the UART functionality I use http://glitovsky.com/blog/?p=300 http://glitovsky.com/blog/?p=300
 (I configured the connection as 8N1 at 115200).

 

 The clock configuration below is used with MCLK = 25 MHz ( when I use it with MCLK=16 MHz I cannot communicate with the UART module at all ) .
 

  P5SEL |= 0x0C;

   /* Select REF0 for FLL reference. */
  UCSCTL3 &= ~SELREF_7;
  UCSCTL3 |= SELREF_2;
 

  /* Set ACLK to use REF0CLK.
    * Set SMCLK to use the DCO.
   */
   UCSCTL4 &= ~SELA_7 & ~SELS_7 & ~SELM_7;
 
   UCSCTL4 |= SELA_2 | SELS_4 | SELM_4;
    /* Initialize FLL. */
    Init_FLL_Settle(mclk/1000L, mclk/32768);
 

    XT2_Start(XT2DRIVE_0);
 

    UCSCTL4 &= ~SELA_7;

     UCSCTL4 |= SELA_2;
    UCSCTL8 |= SMCLKREQEN | MCLKREQEN | ACLKREQEN;
    /* Enable interrupt for TBCCR0. */
     TBCCTL0 = CCIE;
  
   /* Number of ticks per millisecond. */
     clock.aclk = 32768;
     clock.ticks_per_interrupt = clock.aclk / 1000;
     TBCCR0 = clock.ticks_per_interrupt;
 

     /* Use ACLK, set timer to up-count mode, and start timer at zero. */
     TBCTL = TBSSEL_1 | MC_2 | TBCLR;
 

    /* Enable interrupts. */
     __bis_SR_register(GIE);
   
  

 Thanks, 
 Mike