Hook is: Members Online Today 1.1.1 Instructions are: Log in to your IP.Board Admin CP and visit the System tab -> Applications & Modules -> Manage Hooks page. In the 'Install a New Hook' section, browse to the XML file included with these instructions and click Open.
Which is exactly what I am doing.. and it's not the 1st hook I upload in my life.. I've downloaded it about 5 times.. same error. File size is 16kb.. there is text inside too.