Saving text from new richTextBox

[AxOn]

Hi! I'm having trouble creating a save funktion. How can I save the
contens of a new richTextBox that is created from an "external" class
file? The open funktion looks like this:
public void openFile()
{
OpenFileDialog openFileDialog1 = new OpenFileDialog( );
openFileDialog1 .Title = "Select a Text File";

if (openFileDialog 1.ShowDialog() == DialogResult.OK )
{
StreamReader sr = new
StreamReader(op enFileDialog1.F ileName);
string title =
Path.GetFileNam e(openFileDialo g1.FileName);
TabPage myTabPage = new TabPage(title);
tabControl1.Tab Pages.Add(myTab Page);
int index = tabControl1.Tab Pages.IndexOf(m yTabPage);

//Add the RichTextBox to the tabPage.
NumberedTextBox .NumberedTextBo xUC textBox = new
NumberedTextBox .NumberedTextBo xUC();

this.textBox.ri chTextBox1 = new
System.Windows. Forms.RichTextB ox();

// Load the contents of the file into the RichTextBox.
textBox.richTex tBox1.LoadFile( openFileDialog1 .FileName,
RichTextBoxStre amType.PlainTex t);
this.tabControl 1.TabPages[index].Controls.Add(t extBox);

// Active tabPage is the new tabPage.
this.tabControl 1.SelectedTab = myTabPage;

sr.Close();

So the file i want to save is the loaded contens of
textBox.richTex tBox1. The save funktion i made(doesn't work) looks like
this:

private void saveFile()
{

// Create a SaveFileDialog to request a path and file name
to save to.
SaveFileDialog saveFile1 = new SaveFileDialog( );

// Initialize the SaveFileDialog to specify the extension
for the file.
saveFile1.FileN ame = tabControl1.Sel ectedTab.Text;
saveFile1.Defau ltExt = "*.pon";
saveFile1.Filte r = "Point (*.pon)|*.pon|L una
(*.lun)|*.lun";

// Determine if the user selected a file name from the
saveFileDialog.
if (saveFile1.Show Dialog() ==
System.Windows. Forms.DialogRes ult.OK &&
saveFile1.FileN ame.Length > 0)
{
// Save the contents of the RichTextBox into the file.
this.boxen.rich TextBox1.SaveFi le(saveFile1.Fi leName,
RichTextBoxStre amType.PlainTex t);