Cross Page postback, public methods return null

Question

Hi,
I am having problems with transferring data using cross-page. The public methods which supposed to return the value from the previous page textboxes, always returns null.
Code from the present page (CrossPage2) as follows:
  public partial class CrossPage2 : System.Web.UI.Page
  {
  protected void Page_Load(object sender, EventArgs e)
  {
  if (PreviousPage != null)
  {
  lblinfo.Text = "You came from a page titled " +
  PreviousPage.Title + "<br />";
  CrossPage1 prevPage = Page.PreviousPage as CrossPage1;
  if (prevPage != null)
  {
  lblinfo.Text += "You typed in this: " + prevPage.FullName;
  }
  else
  {
  //lblinfo.Text = "null";
  }
  }
  }
}

Code from the previous page (CrossPage1) as follows:
  public partial class CrossPage1 : System.Web.UI.Page
  {
  protected void Page_Load(object sender, EventArgs e)
  {
  }
  public TextBox FirstNameTextBox
  {
  get { return txtFirstName; }
  }
  public TextBox LastNameTextBox
  {
  get { return txtLastName; }
  }
  public String FullName
  {
  get { return txtFirstName.Text + " " + txtLastName.Text; }
  }
  }

Can someone please help me find out what's wrong here.
(I am using ASP.NET 4)

Thank you
Viki