check values in if/else

[kadijsha]

Hello,
I have a problem in performing an if/else with two variables. I´m new in this and I don´t how to this.
Here´s my code. I read the values of the two variables $Play and $Install, both are checkboxes. If nothing is selected a message box should appear. If $Play is selected the installer quit and the game will be started. If $Install is selected I will continue with the installer.

PHP Code:

!insertmacro MUI_INSTALLOPTIONS_READ $Play "test.ini" "Field 4" "State"
!insertmacro MUI_INSTALLOPTIONS_READ $Install "test.ini" "Field 5" "State"
 ${If} $Play == 0 && $Install == 0
 # message box appears
 MessageBox MB_OK "Please select...!"
 ${Else} {If} $Play == 1
 # start game and quit installer 
 Exec "test.exe"
 Quit
 #${Else}{If}$Install == 1
 # go to next page installer?????
 ${EndIf} 


Can you please help me with this if/else. How can I ask for values of two variables, I can´t use "&&". I don´t know how to do. What command can I use to continue with the installer.
Thank you very much.