How to single sign on to Sentinel 8.0 with Access Gateway formfill policy

Access Manager setup and working well ie. users can authenticate at the Identity Server and access a protected resource behind the Access Gateway (AG). Admin wants to single sign on to Sentinel 8.0 portal, and enables formfill to populate the HTML form. After applying changes and updating AG, the user cannot single sign on to the Sentinel Portal - with auto submit disabled, the form is populated but when it is enabled, the credentials are never submitted.

Enable the following formfill parameters:

- input field name: vm.username (with value of LDAP credentials:LDAP User Name  if you want your IDP login credentials submitted)
- input field name: password (with value of LDAP credentials:LDAP Password if you want your IDP login credentials submitted)

- enable auto submit
- enable javascript handling
- populate 'Statements to execute on submit' to be following:

var input = document.createElement('input');
input.type = 'hidden';
input.name = 'User[lang]';
input.value = 'eng';
document.forms[0].appendChild(input);
document.forms[0].elements["vm.username"].name= 'username';
document.forms[0].action = "/sentinel/views/logon.html";
document.forms[0].method = "post";