GRUB does not load "kernel"

I have tried to boot very minimal multiboot "kernel" with GRUB 0.5.96.1 (found an ready-to-use FAT12 image with it). Here is the source:

Code:


OS_LOAD_ADDR equ 100000h

        use32
        org OS_LOAD_ADDR                ; kernel load address

;-----------------------------------------------------------------------------
; Multiboot header
;-----------------------------------------------------------------------------
MBOOT_HEADER_MAGIC equ 1BADB002h
MBOOT_HEADER_FLAGS equ 00010003h

        align 4
multiboot_header:
        dd MBOOT_HEADER_MAGIC
        dd MBOOT_HEADER_FLAGS
        dd 0-MBOOT_HEADER_MAGIC-MBOOT_HEADER_FLAGS
.aout_kludge:
        dd multiboot_header
        dd OS_LOAD_ADDR
        dd load_end
        dd 0
        dd real_entry

;-----------------------------------------------------------------------------
; Kernel entry from bootloader
;-----------------------------------------------------------------------------
real_entry:

        mov     dword [0B8000h], "OOSS"

        hlt
        jmp     $


load_end:

When I try to boot this, GRUB outputs:

Quote:

Booting 'Boot MyOS'

root (fd0)
Filesystem type is fat, using whole disk
kernel /myos/system/kernel.sys

Error 13: Invalid or unsupported executable format

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