User_registration form problem

Sorry I once posted on the wrong issue, here http://drupal.org/comment/edit/979466.

I have a problem when trying to merge user registration form into my user-login.tpl page, either through a block administration or embedding directly into it. They did both appear in the page. But when I log in as usual, after hitting the submit button, I always have a message, like Username field is required, E-mail address field is required which all belong to user_register form. It seems that user-login.tpl conflicts with the registration formblock submit button. Am I doing wrong?

Thanks