i2c code for communication between 89c51rd2 and 24c256

hi i have a problem i communicating with 24c256 from 89c51rd2. i have used the same i2c code to communicate with the rtc and it works fine. please help me to solve this problem .....my code is as follows

#include "lcd.h"
#include <REG51.H>
#include<stdio.h>
#include<stdlib.h>
#include<intrins.h>

sbit sda=P2^1;
sbit scl=P2^0;

#define not_ack 0
#define ack 1
void delay_50msec();

void i2cstart();
void i2cstop();
bit i2cclock();
bit i2cwrite(unsigned char );
unsigned char I2CRead(bit );
bit writei2cport(unsigned char , unsigned char );
unsigned char readi2cport(unsigned char );
void send();
void main(void)
{ char byte2='9'; bit status=1;

init_lcd(); cmd_write(0x80); delay_50msec(); data_write(byte2); delay_50msec();

i2cstart(); status=1; while(status=i2cwrite(0xa6)); status=1; while(status=i2cwrite(0x00)); status=1; while(status=i2cwrite(0x00)); status=1; while(status=i2cwrite('6')); i2cstop();

i2cstart(); status=1; while(status=i2cwrite(0xa6)); status=1; while(status=i2cwrite(0x00)); status=1; while(status=i2cwrite(0x00)); //i2cstop(); i2cstart(); status=1; while(status=i2cwrite(0xa7)); status=1; byte2=I2CRead(0); i2cstop(); delay_50msec();

data_write(byte2); delay_50msec(); data_write('4'); delay_50msec(); //send(); while(1);

}

void i2cstart(void)
{ sda=scl=1; _nop_(); _nop_(); sda=0; _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); scl=0;
}

void i2cstop(void)
{ sda=scl=1; _nop_(); _nop_(); sda=1; _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); scl=0;
}

bit i2cclock(void)
{ bit level; scl=1; _nop_(); _nop_(); while(!scl); _nop_(); _nop_(); _nop_(); level=sda; _nop_(); _nop_(); scl=0;
return(level);
}

bit i2cwrite(unsigned char byte)
{ unsigned char mask=0x80; while(mask) { if(byte & mask) sda=1; else sda=0; i2cclock(); mask>>=1; } sda=1; return(i2cclock());
}

unsigned char I2CRead(bit a)
{ unsigned char mask=0x80; unsigned char byte=0; while(mask) { if(i2cclock()) byte|=mask; mask>>=1; } if(a) { sda=0; i2cclock(); sda=1; } else { sda=1; i2cclock(); } return (byte);
}

bit writei2cport(unsigned char add, unsigned char databyte)
{ bit status; status=1; i2cstart(); if(!i2cwrite(add)) { if(!i2cwrite(databyte)) status=0; } i2cstop(); if(!status) delay_50msec(); return(status);
}

unsigned char readi2cport(unsigned char add)
{ unsigned char khit; bit status=1; i2cstart(); if(!i2cwrite(add|0x1)) { status=0; khit=I2CRead(not_ack); } i2cstop(); return(khit);
}

void delay_50msec() {

TMOD=0x01;

TL0=0xb0;

TH0=0x3c; TR0=1; while(!TF0); TF0=0;

}