RTCOFIFG is always set

Hi

I am implementing RTC in  MSP430F5335. For that i have written my code to configure the clocks as follows

UCSCTL4 = 0x0044; // select ACLK source as XT1 clk

UCSCTL6 = 0xC1CC; // XT1 on in bit 0

while(ucsctrl7 & 0x0002)
{
   ucsctrl7 &= ~(0x0003);  to clear XT1LFOFFG,DCOFFG
   sfrintflag &= ~(0x0002); to clear OFIFG
}

ucsctrl6 |= 0x00CC; 

but after downloding my code in to the controller the RTCOFIFG is always set. At the same time OFIFG is set in SFRIFG1 register and XTLFOFIFG in UCSCTL7 also set. So that i can't able to run RTC.
I tried with the OFIFG interruptservice routine code to clear OFIFG. The code as follows

#pragma vector=UNMI_VECTOR
__interrupt void UNMI_ISR(void)
{
    volatile unsigned int i;
    do
    {
        UCSCTL7 &= ~(XT1LFOFFG + DCOFFG);       // Clear XT1 & DCO fault flags
        SFRIFG1 &= ~OFIFG;                      // Clear OSC Fault flag
        //for (i = 0x0FFF; i > 0; i--);           // Time for flag to set????
        P1OUT ^= BIT0;                          // Toggle P1.0 
    }while ( (SFRIFG1 & OFIFG) );

but still the problem persists in my code. I have referred the discussion in the link

http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/203270.aspx

As per that the backup power system LOCKBAK bit clear is applicable for MSP430F5335 also.
Could anyone clarify why the problem is occurs? Is there any reference available to LPM3 with RTC alrm implementation.

Thanks in advance.