Another item which may come to light is bringing the excel app to the foreground. There are windoze settings which might need to be chagned in order to make the excel window appear in the foreground rather than the background.
I had an RSView application which I added buttons to open up calculator and excel files, but when they don't appear, I found that the user would keep presseing the button, opening multiple instances of the application.
Once, I found 10 copies of calculator running in the background since the taskbar was hidden, it went unnoticed. Once I applied the changed to windows system variablesw to allow the Appstart command to bring focus to the newly started application, the problem was resolved.
It has been many years ago, so I can't quote specifics, but the solution is simple, once you find it.
Paul