Multi domain authentication -- LDAP and SSO

Hi All,

I have configured access policy as in the image. user gets a custom logon page and doesnt have any domain selection tab/drop down. User only need to enter username and password. LDAP -- server configured has details of both domain.

I have two domains one is gr and other is grp. gr domain users are successfully able to login but grp users are unable to login. Kindly update how to add searchDN query for both domains.