I have finally completed my first ArcGIS-task, creating a shapefile containing poligons which mark designated spaces as well as installed facilities. The more than 450 facilities have a whole lot of attributes, luckily accecssable in an Excel sheet which also contains XY-data. I though I had successfully joint this data with the shapefile (as they have one attribute in common), just to realise right after that I can neither edit these nor use them for analyzing.
I have already tried creating a point feature class. As the data is in spanish, I assume the problem might be related with the content (e.j. ñ?).