IES files

I don't know if I am doing something wrong here, but I have repeatedly tried to create custom light fixture families and utilize manufacturer-provided IES files for the lighting distribution. I switch the source to Photo-web and then I browse to locate the IES file. I expect to see a the light source object's shape to mimic the lighting distribution, but all I get is a representation that I would expect for a point source. What am I missing here? Do I have to copy the IES files to the folder in the RAC? I would prefer to leave them in an IES folder in our office library.

The light source 3d graphic in the family will not change. Its photometric distribution in the project will change.

I think you are encountering a typical Revit bug. Try this:
-Close Revit
-Reopen Revit and the fixture file
-Select any other IES file and click apply
-Select the correct IES file and click apply

For some reason Revit just sucks at IES files and the only way to fix it is to to the step above. Please post a screenshot of your fixture if these steps don't work.