palindrome in assembly

[nihade]

hello Friends,, i need your help please
i don't understand where is the problem in my code it blocked in "the print reverse" step
help me please !! with a simple explanations because i'm new in this
thanks

DATA SEGMENT
        STR1 DB "ENTER YOUR STRING HERE ->$"
        STR2 DB "YOUR STRING IS ->$"
        STR3 DB "REVERSE STRING IS ->$"
        INSTR1 DB 20 DUP("$")
        RSTR DB 20 DUP("$")
        NEWLINE DB 10,13,"$"
        N DB ?
        S DB ?
        MSG1 DB "STRING IS PALINDROME$"
        MSG2 DB "STRING IS NOT PALINDROME$"
        A DB "1"

DATA ENDS

CODE SEGMENT
        ASSUME DS:DATA,CS:CODE
START:

        MOV AX,DATA
        MOV DS,AX

        LEA SI,INSTR1

;GET STRING
        MOV AH,09H
        LEA DX,STR1
        INT 21H

        MOV AH,0AH
        MOV DX,SI
        INT 21H


        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

;PRINT THE STRING

        MOV AH,09H
        LEA DX,STR2
        INT 21H

        MOV AH,09H
        LEA DX,INSTR1+2
        INT 21H

        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

;PRINT THE REVERSE OF THE STRING

        MOV AH,09H
        LEA DX,STR3
        INT 21H

        MOV CL,INSTR1+1
        ADD CL,1
        ADD SI,2

     L1:
        INC SI

        CMP BYTE PTR[SI],"$"
        JNE L1

        DEC SI

        LEA DI,RSTR

     L2:MOV AL,BYTE PTR[SI]

        MOV BYTE PTR[DI],AL

        DEC SI
        INC DI
        LOOP L2

        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

        MOV AH,09H
        LEA DX,RSTR
        INT 21H


        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

;PRINT THE STRING IS PALINDROME OR NOT

        LEA SI,INSTR1
        LEA DI,RSTR

        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

        ADD SI,2

     L7:
        MOV BL,BYTE PTR[DI]


        CMP BYTE PTR[SI],BL
        JNE LL2


        INC SI
        INC DI

        MOV BL,BYTE PTR[DI]

        MOV AH,02H
        MOV DL,BL
        INT 21H

        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H



        CMP BYTE PTR[DI],"$"
        JNE L7

        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

        MOV AH,09H
        LEA DX,MSG1
        INT 21H

        JMP L5

     LL2:
        MOV AH,09H
        LEA DX,NEWLINE
        INT 21H

        MOV AH,09H
        LEA DX,MSG2
        INT 21H
     
     L5:

        MOV AH,4CH
        INT 21H


CODE ENDS
END START


;OUTPUT:-
;Z:\SEM3\SS\21-30>P26
;ENTER YOUR STRING HERE ->ANKIT
;YOUR STRING IS ->ANKIT
;REVERSE STRING IS ->
;TIKNA


;STRING IS NOT PALINDROME