Jhones

I'm in need of a help, I'm new to php, it's the first time I've modified an advanced php code like this. I wanted to make an edit inside the tag that adserver generates. Here's an example in the imagebelow: I made a small edit in the invocation.php file where I believe it is correct to perform the tag editing. But when I check if the adserve modified the tag according to my changes, it stays with the old tag without any changes. I want to understand where I am wrong, are there more than one file that I need to edit in order for the tag to be modified?