Solved Canceling chat message?

"Allowed OnPlayerChat to be cancelled for chat."
How can i cancelled chat? Can you please give me example for it?

 

`OnPlayerChat(PlayerSession, string)': not all code paths return a value
What i need to return when mess is no need to be canceled?

 

return null;

 

not work

 

Workes perfect with null, thanks

 

Code:

object OnPlayerChat(PlayerSession session, string message)
{
    if (message.Contains("Hi") return null;
}

not work help please

 

Code:

object OnPlayerChat(PlayerSession session, string message)
{
    if (message.Contains("Hi")) return true; //canceled mess
    return null;
}

 

Code:

object OnPlayerChat(PlayerSession session, string message)
{
    if (message.Contains("Hi")) return false;
    return null;
}

 

http://i.hizliresim.com/1MjN9b.png

 

forgot a ) to close the if

 

Code:

object OnPlayerChat(PlayerSession sessionan, string messagen)
    {
    if (messagen.Contains("deneme")) return false;
    return null;
    }    

no errors but not work :/

 

try message.ToLower()

 

ı not understand, please example code please.
Edit: THANK YOU