I need to compile this code with masm611 but it doesn not work!! what is the problem?

STSEG SEGMENT  
B 64 DUP (?)
STSEG ENDS


DTSEG SEGMENT
;From Data segment
ORG 10H Data_in DB 3FH,21H,0C4H,0A2H,0FFH,0E2H
ORG 28H Copy DB 6 DUP (?)
DTSEG ENDS

CDSEG SEGMENT
MAIN PROC FAR
Assume CS:CDSEG,DS:DTSEG,SS:STSEG
MOV AX,DTSEG
MOV DS,AX
;From Code segment 
MOV CX,06H
MOV SI,offset Data_in
MOV DI,offset Copy
Copy_MOV:MOV AL,[SI]
MOV [DI],AL
INC SI
INC DI
DEC CX
JNZ Copy_MOV
MOV AH,4CH
INT 21H
MAIN ENDP
CDSEG ENDS
END MAIN