assembly - INT 21h does not print -

i wonder why procedure not print:

print: push ax push bx push dx mov ah, 02h        ciclo: mov al, [si]    int 21h inc si loop ciclo  pop dx pop bx pop ax  ret 

according here, calling int 21h while ah 2, prints on stdout ascii code contained in al. while debugging found nothing...

it print character in dl (see this reference).

for example, if dl contains decimal value 65, print character a (since 65 ascii code 'a')