Cross Paging in C# giving error

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C#

I am trying to do paging and following is the code for page 2:

if (this.PreviousPage != null)
{
TextBox TextBox1 = (TextBox)this.PreviousPage.FindControl("TextBox1");
Calendar Calendar1 = (Calendar)this.PreviousPage.FindControl("Calendar1");
Label1.Text = Convert.ToString("Hello {0}!!!! u have selected date as {1}" + TextBox1.Text.Trim() + Calendar1.SelectedDate);
}

it does not display the label text and also if i try remove the if() then it gives the error "Object reference not set to an instance of an object."
Please help