I have two shapefiles, one is polygons, representing geographic areas, and the other is the road network. I want to use Summarize Within tool to summarize the total mileage of roads by the polygon. As soon as I select the layers in the tool's menu, the system automatically creates a name for the output file with the extension of 'shp'. See the picture attached. It also shows an error message: Error 003396 Tool output can only be written to a filegeodatabase(.gdb), datastore (.sde), or in_memory. The problem is that I can not change it! I type in another name like output.gdb and press enter, but the system ignores this. Could you suggest a way to deal with this issue?