Custom Login Form

We have created a custom login page similar to the Quickr default login page and we’re doing a POST to Main.nsf?Login so we can get the LtpaToken cookie in order to use SSO.On the first login attempt, we can’t seem to retrieve the LtpaToken cookie. Another attempt is needed to get it. So a double POST (or one GET and one POST) is needed to successfully log in.

Is this a known issue or is there a step missing in our process?

Thanks