No exception yet no correct result while decryption

Hii.....i made a program for encryption and decryption of files usign rijndael.can anyone guide me what's the problem with this code because it is not giving me any error or exception yet no correct decryption takes place.Button1_click is for encryption and button2_click is for decryption.

byte[] tmpSource;
        byte[] tmpHash;
protected void Button1_click(object sender, EventArgs e)
        {
            if (FileUpload.HasFile)
            {
                tmpSource = ASCIIEncoding.ASCII.GetBytes(this.TextBox1.Text);
                tmpHash = new MD5CryptoServiceProvider().ComputeHash(tmpSource);
& ...