Forms Authentication not working

I have setup simple form authentication with Logon and Logout pages as follows:

Web.config:

<authentication mode="Forms">
      <forms loginUrl="Logon.aspx" name=".MyCookieName">
      </forms>
    </authentication>

    <authorization>
      <deny users="?" />
    </authorization>

    <sessionState mode="InProc" cookieless="false" timeout="20" />

 Logon.aspx:

TimeSpan timeout =
                TimeSpan.Parse("1");

            DateTime cookieCreationTime = DateTime.Now;
     ...