Getting version number error

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C#

I use the following code to get the version of the application that's running:

try
               {
                   string currentVersion = System.Reflection.Assembly.GetCallingAssembly().GetName().Version.ToString();
                   FileVersionInfo myFI = FileVersionInfo.GetVersionInfo("FileName.exe");
                   currentVersion = myFI.FileVersion;
               }
               catch (Exception ex)
               {
                   setDebugText("Error retrieving version number: " + ex.Message);
               }

Most of the time this works, however on some computers an error is thrown, and I can't replicate the error on my computer. What can cause reflection to throw an error, and how can I replicate these conditions on my work computer. Any help will be appreciated.

Edit: For some reason the error outputted to a textbox is Filename.exe. All it give me is the name of the executable that threw the error.

Edit: I have found that the error is caused by the line

FileVersionInfo myFI = FileVersionInfo.GetVersionInfo("FileName.exe");
                  currentVersion = myFI.FileVersion;

I have commented this out and use the function GetExecutingAssembly() instead of GetCallingAssembly and this got rid of the error. I would still like to know why this line would cause problems on a few computers though. Thanks for your comments so far.