Get Window Title by ApplicationName.exe

Question

Why does the code line under ❶ Nothing found fire when I call the below C# .dll like so:

WindowNameGetter::GetWindowName("MyAppName.exe");

(...and "MyAppName.exe" really is up and running!)

C# .dll code:

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

public class WindowNameGetter
{
    // Import the FindWindow function from the user32.dll library
    [DllImport("user32.dll")]
    private static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    // Import the GetWindowText function from the user32.dll library
    [DllImport("user32.dll")]
    private static extern int GetWindowText(IntPtr hWnd, out string lpString, int nMaxCount);

    // Define a public static method named GetWindowName that takes an application name as a parameter and returns a string
    public static string GetWindowName(string applicationName)
    {
        // Initialize an empty string variable to store the window name
        string windowName = "";

        // Get an array of processes with the specified application name
        Process[] processes = Process.GetProcessesByName(applicationName);

        // Check if there is at least one process with the specified application name
        if (processes.Length > 0)
        {
            // Get the window handle of the first process in the array
            IntPtr hWnd = processes[0].MainWindowHandle;

            // Call the GetWindowText function to retrieve the window name associated with the window handle
            GetWindowText(hWnd, out windowName, 256);
            // Return the retrieved window name
            return windowName;
        }
        else
        {
            // ❶ Nothing found:
            return "Error: no process called " + applicationName + " found!";
            }
    }
}