Simple BASIC microcontroller programming question

I would like to input 10 bit from port B pin 0, 1, 2, 3 and output it to
port D pin 2, 3, 4, 5, however, my code seem doesn't work. Could you guy
please give me some idea and point out the mistake.

Bascom AVR complier, Atmel AT90S8535.

The code is shown as below

$regfile = "8535DEF.dat"
$crystal = 8000000


Config Portb = Input
Config Portd = Output

Dim R As Word , W As Byte

Do

  Ddrb = &B11110000                                         'set pin 0,1,2,3
as input
  R = Portb

  Ddrd = &B00111100                                         'set pin 2,3,4,5
as input
  Portd = R
Loop
End