my LCD

hi all
i have a problem with the LCD
my problem is that i don't know what is the wrong ,i write the program and test it using Proteus and the LCD is working on the program
i do double check the wire but no thing is happen all what i see is
a black boxes then after a while they dissapper, for pin 3 i do the voltage divier in order to get small voltage (less than 5volt),and same problem
i heard that the Proteus may not give the correct job....

this is my program :
#define F_CPU 8000000UL // crystal frequency in Hz

#include <ctype.h>

#include <stdint.h>

#include <stdio.h>

#include <avr/io.h>

#include <avr/pgmspace.h>

#include <util/delay.h>

#define setbit(port, bit) (port) |= (1 << (bit))

#define clearbit(port, bit) (port) &= ~(1 << (bit))

void my_delay(int ms) //Delay function

{

int i;

for(i=0; i< ms ; i++)

_delay_ms(1);

}

void write(unsigned char z) // function in inorder to write on LCD

{

PORTD=z;

setbit(PORTB,1);

_delay_ms(10);

setbit(PORTB,2);

_delay_ms(10);

clearbit(PORTB,2);

_delay_ms(10); //wait until the LCD finished execution

}

void startLCD()

{

//** 1) Set function set **//

PORTD=0b00111000; //0x38 in hex

clearbit(PORTB,1); //RS=0

_delay_ms(10);

setbit(PORTB,2); // enabled(toggel)

_delay_ms(10);

clearbit(PORTB,2); //unenabled

_delay_ms(10);

//** 2) display ON / OFF control **//

PORTD=0b00001111;

clearbit(PORTB,1);

_delay_ms(4205);

setbit(PORTB,2);

_delay_ms(10);

clearbit(PORTB,2);

_delay_ms(10);

//** 3) clear display **//

PORTD=0b00000001;

clearbit(PORTB,1);

_delay_ms(10);

setbit(PORTB,2);

_delay_ms(10);

clearbit(PORTB,2);

_delay_ms(10);

//** 4) Entry mode **//

PORTD=0b00000110;

clearbit(PORTB,1);

_delay_ms(10);

setbit(PORTB,2);

_delay_ms(10);

clearbit(PORTB,2);

_delay_ms(10);

}

int main()

{

DDRB = 0x06; // making pin (1) of port D as input and mask others

DDRD = 0xFF; // making all of port B pins as outputs

// delay until the LCD become Ready

_delay_ms(10);

_delay_ms(10);

startLCD(); // call LCD function

write(0x20);

write('A');

write('B');


return 0;

}