I'm sure there must be a simple reason for this but I can't seem to be able to import a shp file or a feature class from another file or sde geodatabase into a Feature Dataset without getting an error. The feature classes come in fine if I don't don't try to import them into a Feature Dataset. The feature dataset definitely has the same projection as the feature classes I'm trying to import so I don't think that's the problem. The Error I get is ERROR 000210 and just says Failed to convert and cannot create output and Failed to execute (CopyFeatures).
Any ideas what I may be doing wrong here. Seems like something so simple. I'm trying to use the Feature Datasets to better organize my data which I think is there purpose.
Update: So as you can see below, Jason helped me find the answer. As suggested by Matt below, I added a new Idea to the ArcGIS Ideas site. Here is the link to that, so please promote this up if you agree a better error message is needed here: http://ideas.arcgis.com/ideaView?id=08730000000brxl