Error: undeclared (first use in this function)

-----------------------------------------------------------------------

SMBSlave.h

-----------------------------------------------------------------------

.....

#define SMBvariables SV.SMBvar

#define SMBvar_int   SV.SMBint

#ifndef MODULE_SMBUS

  union { volatile unsigned char SMBvar[29][2]; volatile unsigned int SMBint[29]; } SV;

char str_MfrName[]    PROGMEM = "\014Atmel Norway"; //__flash char

char str_DeviceName[] PROGMEM = "\005SB100";

char str_DeviceChem[] PROGMEM = "\004LION";

char str_MfrData[]    PROGMEM = "\013MfrDataArea";

#else

  extern union { volatile unsigned char SMBvar[29][2]; volatile unsigned int SMBint[29]; } SV;

#endif

.......

-----------------------------------------------------------------------

communication.c 

-----------------------------------------------------------------------

#include <avr/interrupt.h> 

#include "SMBSlave.h"

.....

ISR(TWIBUSCD_vect)

{

  //clear bits per sbdat110, 4.4.2

  SMBvariables[SMBV_BattMode][hibyte] &= ~(0xE3);  

  if(TWBCSR & (1<<TWBCIP))  //this int was caused by bus DISCONNECT event.

  {

    TWBCSR &= ~(1<<TWBCIP);

//SH    ChangePowerMode(POWERMODE_IDLE,0);

  }

  else  //this int occurred due to a bus CONNECT event.

  {

    TWBCSR |= (1<<TWBCIP);

//SH    ChangePowerMode(POWERMODE_ACTIVE,0); 

  }

}

..

/////////////////////////////////////////////////////////////////////