I often have use for the USDA Soil Data Viewer 6.1, but, since I upgraded to ArcGIS 10.2.2 it will install the add-in, and turn on the toolbar, but will not open the viewer. It gives me the message "Error: Unable to cast object of type 'System._ComObject' to type 'ESRI.ArcGIS.Framework.AppROTClass'." Other people in my company don't seem to have this problem, but they are running a concurrent use license, while mine is a single user. Has anyone else run into this problem? I have uninstalled and reinstalled both the viewer and ArcGIS itself, to no avail.