Dynamic Picture Box in C#.net

I don't know whats wrong with your code. Difficult to understand your exact problem from your question. But in your code I don't see any code to change the label text. One little tip: You change the PictureBox's "Name" during the method, after that you use this name to identify the picturebox. I'd recommend you use the "Tag" property of the picturebox instead to store your "flag" (true/false) to know which picture should be shown.
Anyway changing the properties at runtime should work. Your code seems to work. Just add code to change the label text too.
An example how to handle this situation: Copy/Paste in a new Forms project and replace Program.cs with the following:

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.IO;

namespace PictureBoxWithLabel
{
    static class Program
    {
        [STAThread]
        static void Main()
        {
            // Create an array of sample image paths:
            // For example the pictures located in your systems Common Pictures folder.
            // If you don't have any pictures there, change to any other directory containing image files.
            string strFolderWithPictures = Environment.GetFolderPath(Environment.SpecialFolder.CommonPictures);
            string[] astrImages = Directory.GetFiles(strFolderWithPictures, "*.jpg", SearchOption.AllDirectories);

            int iShownPicture = 0; 

            // Create a test form with 
            Form form = new Form();
            // a Label for some text
            Label label = new Label();
            label.Dock = DockStyle.Bottom;
            label.Text = "Click on the PictureBox!";
            // ... and a PictureBox for viewing an image
            PictureBox picturebox = new PictureBox();
            picturebox.SizeMode = PictureBoxSizeMode.StretchImage;
            picturebox.BackColor = Color.Black;
            picturebox.Dock = DockStyle.Fill;
            // On PictureBox click (or any other event) we re-assign the image for the PictureBox and 
            // the text for the Label - or in other words: change them at runtime.
            picturebox.Click += delegate(object sender, EventArgs ea)
            {
                if (astrImages.Length > 0) // Any images in the sample image directory?
                {
                    PictureBox pbSender = sender as PictureBox;
                    pbSender.Image = new Bitmap(astrImages[iShownPicture]); // change the image
                    label.Text = astrImages[iShownPicture]; // change the text
                    // increment, or reset, shown picture index for next call of this handler
                    iShownPicture = astrImages.Length >= iShownPicture + 1 ? ++iShownPicture : 0;
                }
            };

            form.Controls.Add(label);
            form.Controls.Add(picturebox);

            Application.Run(form);
        }
    }
}