log-in option from top bar of my newspaper is not working

I put a ‘login / join’ options for my subscriber in header’s top bar.

Subscribers of my newspaper can register as a ‘contributor’ from that option but can’t login from there.

Whenever they are trying to login they got message that, ‘User or password incorrect!’. Whereas user and password both are correct and with that user id and password newly registered contributor can login from wp-admin panel.

Please take look in that issue and solve it ASAP. Thanks!

My URL:
http://amrai71.com

Dear Catalin,

Thanks for your reply. At first, I am using the latest version of theme 9.5. And I have the following:

Active plugins 6 items:
1) Google Captcha (reCAPTCHA) by BestWebSoft (Version 1.41) ; By BestWebSoft
2) Regenerate Thumbnails (Version 3.1.0) ; By Alex Mills (Viper007Bond)
3) tagDiv Cloud Library (Version 1.0 BETA) ; By tagDiv
4) tagDiv Composer (Version 2.3) ; By tagDiv
5) tagDiv Social Counter (Version 4.5) ; By tagDiv
6) WP Super Cache (Version 1.6.4) ; By Automattic

In Must-Use tab there is one plugin
1) Endurance Page Cache (Version 1.3) ; By Mike Hansen

In Drop-ins tab there is one plugin
1) advanced-cache.php ; details are not available

I could register as a test contributor (ID: shariful_hamid) from header’s top bar but when I tried from there it shows, “User or password incorrect!”. Whereas, I can login using same id & password from amrai71.com/wp-admin.

Please help me in this regard.

My URL:
http://amrai71.com/