Microsoft offers a range of Add-Ins and other extensions to Excel’s normal functionality. These are accessed most easily from the ‘Developer’ ribbon. The Developer Tab Clicking the Add-Ins icon, offers the user a list of all Add-Ins currently available to your Excel program. The problem comes when your particular program isn’t listed there. Even when you know where the Add-In file is and double click it, the functionality is still not activated. According to SuperUser.com , the problem results from security patch in KB31152, released in July 2016. Apparently, Microsoft software engineers have said: "With this update, we changed the behaviour of Excel so that it will not load certain file types (including .xlam) when they are untrusted. The easiest workaround is to find the add-in that is causing you trouble, right-clicking on it in Windows Explorer, and checking Unblock" However, SuperUser.com recommend placing the add-in in a Trusted Location (in Excel, go to File