I had an issue with my file. Then I tested it with another file. The issue is same.
I have a 2012 .rvt file. and when I open it in Revit 2013 and delete one of my systems. (Ex: Mech. supply Sys.) I could not create a new system with the same diffusers. I think could not add a video.I will try it with youtube. I am waiting your comments. It is really imoırted for me..!!!! Thanks.