Failure. The API could not validate your log in. Please make sure you have entered the correct Company Account, User and Password, and that each are spelt correctly. Also, ensure that this User has been configured for Method API access by going to Customize > Users, editing the User, and ensuring that there is a check in the 'Is Allowed to Connect via MethodAPI' checkbox.
I've double-checked the credientials and they are correct. I'm also able to return values when using this person's code -- https://www.method.me/cs/forums/p/6818/25395.aspx#25395 Which seems to tell me that my credientials are correct. But that is not the method I'm wanting to use. (I want to use MethodAPIInsertV2). It kind of seems like this error is generic, based on how many times I've seen it listed for various things in the forums.
It would be awesome if there was a Method-approved PHP example in the API docs. By searching in the forums, there's tons of people who have been looking for this, for years.