Thank you for all of your help! The information you sent me was like a lightning strike of knowledge and allowed me to fix the problem quickly and easily. I'll summarize the information here in an attempt to make it easier for other simmers.
Most flight simmers have at some point downloaded freeware aircraft from sites like avsim.com or flightsim.com. In the course of installing these programs, we sometimes have to manipulate the folders and files within the zip files. When FS9 and FSX were released, the Windows operating system of choice was XP. In later versions of Windows the operating system handles installed programs differently and these differences are not readily apparent to old users of XP FS Commander 10 and FS9 or FSX must be NOT installed under the folder Program files(x86) or Program Files. This allows the add on program to "see" the vital, needed files in the FS program. I had already installed FSC10 under C:. I then merely copied the Flight Simulator 9 folder from Program Files (x86) folder to the C folder. This allowed FSC10 to "see" the needed files under the FS9 folder.
As always, YMMV (Your Mileage May Vary)