'New version of Outlook', no thanks

If your using Microsoft Outlook, (i.e. the ~$250 value product that comes with Microsoft office) and you get an option to 'Try the new Outlook' I strongly suggest you don't do that, if you do you you will possibly lose a LOT of functionality and go from the business grade $250 value product to essentially the free web based version that everyone with a Hotmail or outlook.com email account gets for free. A lot of features will disappear including Outlook add-in utility's and any secondary emails you may have setup. 

You can see more detail here on this email from a Microsoft outlook add-in developer.