Most likely you've left a required field blank. Look along the right side of the screen. If you've left a required field blank the right side of the field will turn Red. Some fields will also say "Required" below it.

Here are the required fields:

Please note although the field is required - if you don't have anything to enter please just put 0 (zero).

If you have any other questions please open a chat with me by going to the Chat with Support menu item.