New user registration issue

[Elias 0]

{Sorry for the English but i dont know Russian. I would appriciate any help in English}

hello to DLE members,

I have recently undertake a website build on DLE v8.3

There is an issue with the user registration. When someone register, he receives an "Account activation" email but when he clicks on the activation url he get redirected to this pagehttp://kazani.gr/index.php?do=register&doaction=validating&id=ZWxub3x8Y29udGFjdEB0aGVjeXBydXNndWlkZS5uZXR8fGUxMGFkYzM5NDliYTU5YWJiZTU2ZTA1N2YyMGY4ODNlfHwyMTc1Mjk4ZWY4NTZiNzRmM2IxYjU2NDJkNDk5YjIzZQ%3D%3D which appears with no content. its like the template of this page is missing.

Is the problem somewhere registration.tpl? Can you guide me in order to solve this issue.

this is my website: http://kazani.gr

Also when someone applies to change his password he receives again an empty page: http://kazani.gr/index.php?do=lostpassword

I have tried with another template and is working fine. I know that the propblem exist in my template.

thanks

[Elias 0]

can anyone help?