Delete Registrant Button not working? 1.7.0

Hi I have a strange bug whereby I cant use the delete button (to delete a registrant) because the usual popup that appears "Do you want to remove the selected items? Cancel / Ok" is not showing. Also same for trying to delete Events.
I have cleared the site and browser cache and I can confirm it work on other sites using EB1.7.0 and Joomla 3.4.1.
What do you think is the issue?

Thanks

Sorry Tuan I think its a browser issue (Chrome) as the functions work in FF.
I will try resetting chrome altogether.

OK. I always use chrome and it works well here for me. So I think it is just a computer / browser issue. Please try again and let me know if you still need me to check it

Regards,

Tuan