How to fix this problem?

I need to know how can i fix this problem, when in the login fields somebody enter a wrong user and password my site send it to a blank member.php,i don't want to do that, i want to show a error message to alert that the user or pass is wrong. How can i do that ? I leave you some attach to explain myself. Thanks 

You need to turn on php error reporting. I have a feeling that member.php is throwing an error but reporting is turned off. Also check the error_log file and see if anything is there.

where i find error_log file??

That file should be in any directory where an error was generated so it should be in your public_html (or where ever member.php is).

Sorry, but i don't see it.

If you turn on error reporting in your php.ini the error will be displayed on the screen and you won't need to find the file.

ok thanks, i understand you now.

I don't have errors on my errors log

You showed a screenshot instead of posting a site URL. So i cannot check for proper design of your non standard dolphin logon form.

Who designed the form you show in your first screenshot. Because you should be going to them to resolve the problem.

The way logon forms in dolphin work is the form is verified via a javascript call first before it redirects. If the logon id and password is incorrect, javascript will popup a box indicating invalid logon id and password.

All logon boxes within dolphin work this way. At least all the standard default logon boxes.

Your is not a standard default logon box. So whoever designed it either did not include the default javascript form validation or did not do it correctly.

Thanks deano,if you could tell me how can i show the popup like dolphin does when the user is wrong.