Getting Unknown variable error while compiling c to hex

//GPS and GSM Based Vehicle tracking system
#define F_CPU 12000000			//12Mhz
#include <avr/io.h>			//Header file for AVR device specific I/O Definitions.
#include <avr/pgmspace.h>		//Header file for incorporating program space string utilities.
#include <util/delay.h>			//Header file for incorporating delay routines.
#include<inttypes.h>


#define USART_BAUDRATE 9600
#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)

void WaitMs(unsigned int ms);		

void usart_init();
unsigned int usart_getch();
void usart_writech(unsigned char data);
void usart_message(unsigned char *var);

unsigned char value,i,lati_value[9],lati_dir, longi_value[10], longi_dir, final_message[30];
unsigned char deg = 0xB0;

int main()
{

DDRC=0x00;
PORTC=0xff;

    usart_init();

    while(1)
	{
	 a:
	 value=usart_getch();
	 if(value=='$')
	 {
		
	value=usart_getch();
		if(value=='G')
	{
	value=usart_getch();
	if(value=='P')
	{
	value=usart_getch();
	if(value=='G')
	{
				
	value=usart_getch();
	if(value=='A')
	{
	value=usart_getch();
	if(value==',')
	{
	value=usart_getch();
	while(value!=',')
	{
	value=usart_getch();
	}
	
	for(i=0; i<9; i++)
	{

	lati_value[i] = usart_getch();

	}
	value = usart_getch();
	
	lati_dir=usart_getch();
	value=usart_getch();
	for(i=0; i<10; i++)
	{

	longi_value[i] = usart_getch();
	}
    value = usart_getch();
	
		for(i=1;value!=',';i++)
	{
		longi_value[i]=usart_getch();

		value=longi_value[i];
		}
	longi_dir=usart_getch();
	}
	}
	}
	}
	}
	}
	if(*lati_value && *longi_value)
	{
     for(i=0; i<9; i++)
	 {
	 final_message[i] = lati_value[i];

	  }

  final_message[9] = lati_dir;
  final_message[10] = ' ';
	 for(i=0; i<10; i++)
	 {

	 final_message[i+11] = longi_value[i];
  }

	
	final_message[21] = longi_dir;
	 final_message[22] = '\0';
    }
	else
	 goto a;
	while(PINC==0xff);
     WaitMs(1000);
	 usart_message("ATH");
	 WaitMs(50);

       
	 usart_message("AT+CMGF=1");
	 usart_writech(0x0D);
	 WaitMs(20);
		 
	WaitMs(20);
	usart_message("AT+CMGS=\"+918907607614\"");
	 usart_writech(0x0D);
	 usart_message(final_message);//message
	 usart_writech(0x1A);
	 WaitMs(10000);
		 goto a;
	 
    }


	return 0;	
	
}


void WaitMs(unsigned int ms)		
{
	unsigned int i;

	for(i=0;i<=ms;i++)
	{
		_delay_ms(1);
	}
}


 
void usart_init()
{

UCSRB =  (1 << RXEN) | (1 << TXEN);                    

// Use 8-bit character sizes
UCSRC |= (1 << URSEL) | (1 << UCZS0) | (1 << UCZS1);   

// Load lower 8-bits of the baud rate value into the low byte of the UBRR register
UBRRL = BAUD_PRESCALE;  
                              
UBRRH = (BAUD_PRESCALE >> 8);                          
}
 
 
unsigned int usart_getch()
{

while (!(UCSRA & (1 << RXC)));                          

return(UDR);                                            
}

void usart_writech(unsigned char data)
{
 
 while(!(UCSRA & (1<<UDRE)));
 UDR = data;
}

void usart_message(unsigned char *var) 
{
int h;
while(*var)         
usart_writech(var++); // send message
for(h=0;h<=200;h++); 
}