Right, thanks Esri.
For anyone trolling the forums, let me just clarify what was going on;
The .sdlic is the license file for the data, it does not activate the extension. Our organization has 2 ArcGIS license servers, however, our recent annual update did not include business analyst as an extension on our site-wide or departmental license server. So rather than point to a centralized license server to activate the Extension, what we did is set up a local license server on the machine we installed Business Analyst so that we can point to it for Business Analyst extension. We then had to register /authorize the extension and ArcInfo license locally.
So when we use Business Analyst we point the machine to the local license manager and if we want to use, say, Spatial Analyst extension, we point to our license manager on our license server machine.