And there's your problem right there.
Record: 1, Array ( [ID] => 1 [Username] => buddieangel [Password] => nicole1300 )
And used with
$dbusername = $row['username'];
$dbpassword = $row['password'];
Indices are case sensitive. SQL is not.
I also noticed that the error lines do not match up. I assumed whitespace in question or removed sections of code.