First of all, it has once been working properly with one of my Gluu Servers. However, when I try to do the same with another Gluu Server (I have done similar configuration processes as the first one), a problem occurs. When I tried to login with my Google account and clicked the "Sign in" button of Google, I was prompted for my Google account details. (Till now, all seems to be working properly.) However, after entering all my Google account details, the Gluu Server just responds with "Incorrect email or password", and I cannot enter the Gluu Server. (I am sure that my username and password are correct. And, I have tested it with different Google accounts.) Moreover, if I login at the Google web site before entering the Gluu Server, then when I try accessing the Gluu Server, it can show my Google account name at the bottom of the browser window. However, the error message "Incorrect email or password" will then be shown, and I eventually still cannot enter the Gluu Server. Please advise what is the possible mistake I have made which leads to the above mentioned problem?