Hello i had posted my problem
here and it was fixed but after a while i noticed a bug.
My problem was fixed by checking this field in the screenshot.
Attachment Capture.PNG not found
but after that the registration at the checkout page wasn't working.
To be exact the pop up page didn't showed up the registration fields but the login page inside. ( i have checked i don't have enabled the option "Only registered users can checkout ")
If i disable the seo it works perfectly but the next and previous buttons doesn't work... -_-
Can you please take a look.
Thanks in advance.