MSP430FR2355: RTCMOD register not loading?

Part Number: MSP430FR2355

    RTCMOD = (int)((float)(32768 / divA[div]) * s) - 1;  //upper 8 bits are seconds that IRQ will occur
    RTCCTL |= RTCSS__XT1CLK | RTCSR | (div + 4) << 8;

I set a breakpoint after the last line of code seen above.  I look at the RTCMOD register and it is showing me 20479 (decimal).  The value of the expression when copied into the expression window is 255.  Can someone tell me why RTCMOD doesn't seem to be loading the calculated value?

Thanks