Couldn't push value for stack?

I can't push any specific value onto the stack, can someone clear this for me

 DOSSEG
.MODEL SMALL
.STACK 200h
.DATA

Message db "Hello World $"

.CODE

START:
push 9
mov ax,seg Message 
mov ds,ax
mov dx,offset Message 
mov cx,2h
mov ah,9
int 21h 

mov ax,4c00h 
int 21h 

END START

      

        
        
        
      

    

LINE 11: error A2001: immediate operand not allowed