Error Cannot Acquire Connection From Connection Manager

Hi guys, I am struggling with one package built by one of my colleague. Situation: the package is in the folder newrelease (that's important, it comes later in my explanation), the user John has the rights for that folder. I've created the credential John (with username and password) and I've created the proxy_John with credential John. I set up a sql agent job running at 3.00 pm but it doesn't work (even if I run it automatically from SQL Agent). The problem is the connection manager IPExcel. This excel connection manager is structured in \\Network\Department\Folder\Subfolder

Error ClassNotRegistered, CANNOTACQUIRECONNECTIONFROMCONNECTIONMANAGER

Any thoughts?

Thanks