how to add two numbers of 2 digits each

im using this code but it doesnt work when there is a carry on the MSB

VB Code:
  1. .MODEL SMALL

  2. .STACK 200

  3. .DATA

  4. CRLF    DB  0DH,0AH,'$'

  5. PROMPT1 DB  'Enter the first positive integer:  ','$'

  6. PROMPT2 DB  'Enter the second positive integer:  ','$'

  7. PROMPT3 DB  'The sum of the two numbers is:  : ','$'

  8. .CODE

  9. .STARTUP

  10.     LEA DX,PROMPT1

  11.     MOV AH,09H

  12.     INT 21H

  13.  
  14.     MOV AH,01H

  15.     INT 21H

  16.     SUB AL,30H ; convert character to number

  17.     MOV CH,AL

  18.     

  19.     MOV AH,01H

  20.     INT 21H

  21.     SUB AL,30H ; convert character to number

  22.     MOV CL,AL

  23.     

  24.     LEA DX,CRLF

  25.     MOV AH,09H

  26.     INT 21H

  27.  
  28.     LEA DX,PROMPT2

  29.     MOV AH,09H  

  30.     INT 21H

  31.     

  32.     MOV AH,01H

  33.     INT 21H

  34.     SUB AL,30H ; convert character to number

  35.     MOV BH,AL

  36.     

  37.     MOV AH,01H

  38.     INT 21H

  39.     SUB AL,30H ; convert character to number

  40.     MOV BL,AL   

  41.  
  42.     ADD CL,BL

  43.     ADC CH,BH

  44.  
  45.     ADD CL,30H ; convert number to character

  46.     ;ADD CH,30H

  47.     

  48.     LEA DX,CRLF

  49.     MOV AH,09H

  50.     INT 21H

  51.  
  52.     LEA DX,PROMPT3

  53.     MOV AH,09H  

  54.     INT 21H

  55.  
  56.     MOV DL,CH

  57.     MOV AH,02H

  58.     INT 21H

  59.  
  60.     MOV DL,CL

  61.     MOV AH,02H

  62.     INT 21H

  63.     

  64. .EXIT

  65. END

can someone help