why multiple condition in python while loop are not working? : <p>I can't seem to find the problem in code...<br></p>

<pre><code>user_decision = ""
while not user_decision == "yes" or not user_decision == "no":
    user_decision = input("You want to Join?: Please answer (yes/no): ")
else:
    if user_decision == "yes":
        print("test")
    else:
        print("test")
</code></pre>

<p>Thanks....</p>
