If you cannot submit the registration form, this problem may occur when you have failed to fill in some required fields. Therefore, go back to the registration form and check whether you have provided all details. If you have provided all information but the form still does not submit, check the attached files. When you attach to many files that exceed the limit or the format of which is not supported, there may be some problems with the order placement. In such case, after you delete these files from the order placement form, the page will proceed your operation. Instead, you can send all the files via email to our customer support team. Please remember to enter your paper ID in the subject field of your email.