NASM error: parser instruction expected

Question

 ;**********************************
 ; Boot1.asm
 ;      - A Simple Bootloader
 ;   Operating System Development
 ;**********************************

    org 0x7c00    ;BIOS loaded at 0x7c00

    bits 16       ; We are still in 16 bit real mode

     Start:
     cli      ; clear all interrupts
     hlt      ; halt the system

     times 510 - ($-$$) db 0  ;We have to be 512 bytes.Clear rest of bytes with 0

     ddw 0xAA55               ;Boot signature

I wrote a simple boot boot in nasm on Windows 7, but I get an error:

 error:parser: instruction expected.

This problem has been resolved earlier, but I do not understand it in my context.

Answer 1

NASM docs do not specify assembler directive ddw. I expect what the error message says. ddwis not an "instruction", so it gets confused.