RTC updating problem

Dear sir,
I am interfacing DS1307 with ATMEGA16.displaying the time in 7 segment display.7segment scanning time is 1 sec. Problem is rtc is not updating and i am using 32.768Khz crystal in DS1307.So kindly tell me the solutions for this problem.
Thanks in advance....

@ kathirdot
we can help you better after posting your code
may be something wrong in coding

Dear sir,
thanks for your response.i am posting the code here.Pls let me know what are the problem in this code...

#define F_CPU 16000000UL
#include<avr/io.h>
#include<util/delay.h>
#include <util/twi.h>
#include <inttypes.h>
void TWI_init();
void TWI_start();
void TWI_stop();
void TWI_ack(unsigned char ackval);
void TWI_write(unsigned char data);
unsigned char TWI_read();
unsigned char readDS1307(unsigned char address);
void Get_rtc();
void Set_RTC();
void WriteDS1307(unsigned char address,unsigned char data);
unsigned char Time[15] ={"22:27:57\r"};
unsigned char Hour,Min,Sec;
int main()
{

DDRA=0xFF;
PORTA=0x00;

DDRC=0xFC;
PORTC=0xF0;

TWI_init();

WriteDS1307(0x07,0x10);

Set_RTC();

while(1)
{
Get_rtc();
}
}

void TWI_init()
{

TWSR=0x00;
TWBR=0x12;
TWCR=0x04;

}

void TWI_start()
{

TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWSTA)|(1<<TWEN);
while(!(TWCR &(1<<TWINT)));

}

void TWI_stop()
{


TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWSTO)|(1<<TWEN);


}



void TWI_ack(unsigned char ackval)
{

TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWEN);
while(!(TWCR & (1<<TWINT)));

}

void TWI_write(unsigned char data)
{

TWDR=data;
TWCR=((1<<TWINT)|(1<<TWEN));
while (!(TWCR & (1<<TWINT)));

}


unsigned char TWI_read()
{

TWCR=((1<<TWINT)|(1<<TWEN));
while(!(TWCR & (1<<TWINT)));
return(TWDR);

}


void Get_rtc()
{

Sec=readDS1307(0x00);
Min=readDS1307(0x01);
Hour=readDS1307(0x02);



Time[7]=Sec&0x0F;
Time[6]=Sec&0xF0;
Time[6]>>=4;


Time[4]=Min&0x0F;
Time[3]=Min&0xF0;
Time[3]>>=4;


Time[1]=Hour&0x0F;
Time[0]=Hour&0xF0;
Time[0]>>=4;

To_7segrtc(Time);

}

unsigned char readDS1307(unsigned char address)

{

unsigned char rcvbyte;
TWI_start();
TWI_write(0xD0);
TWI_write(address & 0xFF);
TWI_start();
TWI_write(0xD1);
rcvbyte=TWI_read();
TWI_stop();
return(rcvbyte);

}


void Set_RTC()
{

WriteDS1307(0x02,0x12);
_delay_ms(100);
WriteDS1307 (0x01,0x16);
_delay_ms(100);
WriteDS1307 (0x00,0x32);
_delay_ms(100);
}

void WriteDS1307(unsigned char address,unsigned char dat)
{

TWI_start();

TWI_write(0xD0);

TWI_write(address);

TWI_write(dat);
TWI_stop();

}

after every write or read operation there must be an ack or nak depending on what you want to do. I see TWI_ack() function calls missing from your code. please fix that.