Yes very shure! Are there any other files to be editted??
In terms of that particular link showing/not showing, there should be no other factors which effect it at all. I will have a think about any other possible ways that this error could be occuring, but your Admin.php file is definitely okay, could you post your Modifications.english.php file so I can check it?
I am not entirely sure what you are talking about, but I am going to add more documentation to the downloads page so hopefully that will explain everything. To post a form, you need to access it from the index.php?action=form, also remember that the form settings in the admin area have to be done properly, ie. the board id has to be valid, there have to be fields in the form and etc.