[MASM32] After calling my function, the program closes. What to do?

Question

assembler

Hello.
There is this code:

...
addValues proc near
  add ebx, ecx
  ret
addValues endp

start: 
  invoke AllocConsole
  
        mov ebx, 10
       mov ecx, 10        

        call addValues

  invoke StdOut, firstMes
    
  invoke ExitProcess, 0
end start

After calling the addValues ​​function, the program closes and does not display the value. Why?