Build error MSP430F2272

this is in main.c

int main(void)
{
    CSL_init();                     // Activate Grace-generated configuration

    while(1)
    {
        CheckSerialCom();
    }
}

I get this error when I build my project:

undefined first referenced                                                                                       
  symbol       in file                                                                                            
 --------- ----------------                                                                                       
 main      C:\ti\grace_1_10_04_36\packages\ti\targets\msp430\rts430\lib\ti.targets.msp430.rts430.ae430<boot.oe430>

There are no additional errors.

Any idea what could be causing it?