Compiler/CC2530: Error[e46] Undefined external error with functions in header files I've included

Tool/software: TI C/C++ Compiler

main.c looks:

#include <stdio.h>
#include <string.h>

#include "hal_mcu.h"

int main( void )
{
halMcuInit();

return 0;
}

hal_mcu.h is included that has related hal_mcu.c file as part of the project. In hal_mcu.c function halMcuinit(); is declared.

I am unable to debug why IAR shows error "Error[e46]: Undefined external "halMcuInit::?relay" referred in main"

Thanks,