How can a path differ between install version and while debugging?

I have the following code that when used while debugging or using the release version of the solution works just fine, but when used with an Install version made from Inno Setup it returns the following error.

System.ComponentModel.Win32Exception
HResult=0x80004005
Message=Le fichier spécifié est introuvable
Source=System

The error result from the following code at line compil start :

compil.StartInfo.FileName = AppDomain.CurrentDomain.BaseDirectory + @"innoFiles\\ISCC.exe";
compil.StartInfo.Arguments = strISSFile;
compil.StartInfo.RedirectStandardError = true;
compil.StartInfo.RedirectStandardOutput = true;
compil.StartInfo.CreateNoWindow = true;
compil.StartInfo.UseShellExecute = false;
compil.EnableRaisingEvents = true;
compil.ErrorDataReceived += Compil_DataReceived;
compil.OutputDataReceived += Compil_DataReceived;
compil.Exited += Compil_Exited;
compil.Start();

This application used to work just fine but I recently needed to make some changes to another part of the solution. The actual .iss file to make the install version of this solution has been lost hence me trying to make a new one.