Trying to load an app through reflection and get error “Could not load file or assembly…The system cannot find the file specified.”

string myDll = string.Empty;
string location = Assembly.GetExecutingAssembly().Location;
if (location != null)
{
    myDll = string.Format(@"{0}my.assembly.name.dll", location.Substring(0, location.LastIndexOf(@"")));
}