In SharePoint 2013, the button "Import Documents" in the ribbon is greyed out.
There are 2 pre-requirements to using "Import Documents" feature in SharePoint 2013:
1. The feature can only supports SharePoint 2013 server, not SharePoint 2013 Foundation.
2. This feature can only supports IE which the Active X is enabled(please refer to http://msdn.microsoft.com/en-us/library/ie/hh920753%28v=vs.85%29.aspx)
Applies for: SharePoint 2013