VS C# 2008 File Dialog

I am trying to present to the user a textbox that will contain a filename, complete with path, that is derived by providing a lookup to where you want this file to go. The textbox is called txtFileName.

I am trying to follow the example in the code provided below but even though I have included the System.Windows.Forms namespace it does not recognize saveFileDialog1 all I get is saveFileDialog and there is no Filter directive. What am I mssing?

private void btnSave_Click(object sender, EventArgs e)
         {
             saveFileDialog1.Filter = "Text Files (*.txt)|*.txt|All Files (*.*)|*.*";
             saveFileDialog1.FilterIndex = 1;
             if (saveFileDialog1.ShowDialog() == DialogResult.OK)
             {
                 StreamWriter myStream = new StreamWriter(saveFileDialog1.FileName, true);
                 myStream.Write(richTextBox1.Text);
                 myStream.Close();
             }
         }

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