我们的舞台简谱:急急急!!!请教一下汇编高手

为什么老是输出"no match",我想知道哪里错了
(以前把str1,str2与m1,m2一起放es,结果打印"asdfg')
str SEGMENT
str1 DB 'asdfg'
s1 LABEL BYTE
str2 DB 'asdfg'
s2 LABEL BYTE
str ENDS
data SEGMENT
m1 label byte
DB 'no match',10,13,'$'
m2 label byte
DB 'match',10,13,'$'
data ENDS
code SEGMENT
ASSUME CS:code,DS:data,ES:str
start: MOV AX,str
MOV ES,AX
MOV AX,data
MOV DS,AX
LEA SI,ES:str1
SUB SI,ES:s1
LEA DI,ES:str2
SUB DI,ES:s2
CMP SI,DI ;比较str1,str2长度
JNE no_match
LEA SI,ES:str1
LEA DI,ES:str2
CLD
REPE cmpsb
CMP SI,ES:s1
JNb match
no_match: LEA DX,m1
MOV AH,09h
INT 21h
jmp out1
match: LEA DX,m2
MOV AH,09h
INT 21h
;
out1: MOV AH,4ch
INT 21h
code ENDS
END start