Asp.net Forms Authentication unable to direct to login Page

Question

My web application includes 3 web forms 1)Login.aspx 2)Default
Also i am using asp.net form authentication with following configuration

<authentication mode="Forms">

      <forms loginUrl="Login.aspx" timeout="30" name="MyAuthCookie" path="/">

      </forms>

</authentication>

When I run my web application(Vs-2010) I expect that it should redirect to login.aspx, but application start with default.aspx or Details.aspx based on which form has focus at design time. I even try it after hosting to IIS but again same result. 

Please suggest what can be Issue.