i try to use pic16f877a for the first time..

i connected the following :

1- 10k resistor to pin 1
2- +5v to pin 11
3- GND to pin 12
4- 4MHz crystal to pin 13,14 just

and i tryed to light a led on portb.0 by this small code:

DEFINE OSC 4
TRISB = %11111110

MAIN:

PORTB.0 = 0

PUASE 200

TOGGLE PORTB.0

PUASE 200

GOTO MAIN

i programmed this code into pic16f84a and worked very well.

but in pic16f877a , there is no any output , led is off for ever.
i changed the crystal, and the voltage regulator, and the problem is still !!!

what is the probelm??