.ShellExecute is a method that is performed on a ShellApplication object. I think it's more generic to VB and jscript. I can't recall if it's compatible with Access vba or not. You have to "tell" Office programs where to find it via declarations (SHELL32.DLL). AFAIK, it's the better approach if the program has associated .lnk files/folders
I doubt that I can help with this one, but will suggest that the code should be provided so that clues might be found as to what the problem is.
OOPS - I see that I'm repeating good suggestions that are already made, but will add that "the program" should be revealed.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.