Owin challenge triggers in the second intent on DNN

Question

I've created a custom login module for DNN with mixing authentications: 1) Authenticate thru ADFS. 2) Authenticate with regular forms authentication. Everything is working except:

protected void Adfs_Click(object sender, EventArgs e)
{
    HttpContext.Current.GetOwinContext()
                .Authentication.Challenge(new AuthenticationProperties { RedirectUri = redirectUrl },
                    OpenIdConnectAuthenticationDefaults.AuthenticationType);
}

the first click reloads the page and always works the second time. I've tried to disable the forms authentications like this post suggest, but because I'm working with DNN I can't do that.

I also test triggering the event on the Page_Load and works, but I want to allow the DNN native users to be able to login direct to DNN (host user) ... so I can't do the challenge there either.

Any help on what should I do to make the challenge works with the first click?

Thanks in advance.