if statement with or comparison (newbie)

I'm trying to set up a simple conditional, something like this: If my_variable is NOT equal to (black or white) echo "wrong color" else echo "right color" Here is what I have tried:

    if ($_REQUEST['id'] != ("black" or "white")) {

        echo "wrong color";

    } else (

        echo "right color";

    )

However, no matter what I enter, I always get response "right color". I should add that if I change the if statement to:

    if ($_REQUEST['id'] != ("black"))

then I get "right color" when I enter "black" and "wrong color" for everything else. Would you please point out what's the trivial thing I'm missing here... jd