3th. Part Radius Captive Portal Live User Login

Please I working on my own external captive portal and every things go fine . but  when user trying to access internet he will redirect to login page but if he inserted  wrong username or password , he must try again but the request does not go to fortigate till user has new magic id .

I don't know if you have same problem , 

I will explain my problem with example(if user insert wrong password or username wrong message will appear to him to try again , but when he insert  his username and password again  fortigate does not do any thing until user trying to access any website he will redirect to login page with new magic id so his information will be process by fortigate )

I think this problem depending on login fail  page which I mad but how can I tell fortigate to redirect user to it  .

please if u have any information help me 

you must working on external captive portal with mysql database so you can access online users and can log any things in your portal