这个汇编程序哪里错了

;---------------------------------
cha macro numb
lea dx, string1
MOV BL, numb
MUL BL
ADD DX, AX
mov ah, 9
int 21h
endm
;---------------------------------
data segment
string1 db 'zhang san $'
chang equ $ - string1
string2 db 'li si $'
string3 db 'wang er $'
string4 db 'xiao hong $'
string5 db 'fang fang $'
string6 db 'ming ming $'
string7 db 'bing bing $'
data ends
;---------------------------------
code segment
assume cs:code,ds:data
start:
mov ax, data
mov ds, ax
mov ah, 01
int 21h ;input: 0~6
and al, 0Fh ;al = 0~6
cha chang
mov ah, 4Ch
int 21h
code ends
end start
;---------------------------------