The problem with trying to learn something on line is that 50 to 75% of the information is worthless, because it comes from amateurs. If you don't use the proper adhesive, supplies, and procedures, you will fail. None of the people who posted asked you what you were doing, they just threw information at you. Did you learn anything from them? Did anyone help you in any way?
If you want to keep failing, just keep listening to the amateurs. If you want to do your door panels correctly, do a search for information such as this: Door panel tutorial