For each loop returns blank

For each loop returns blank

I have a for each loop in the final step of my asp:Wizard that is supposed
to list all of the text in each textbox that is not null. The textboxes
are in the second step of the asp:Wizard and they are placed in asp:Panel
controls that are made visible or not visible with the use of checkboxes
on the same step. Here is the event with the loop:
protected void Wizard1_FinishButtonClick(object sender,
WizardNavigationEventArgs e)
{
var requested = this.Controls.OfType<TextBox>()
.Where(txt => !string.IsNullOrWhiteSpace(txt.Text));
var sb = new StringBuilder();
foreach (var textBox in requested)
{
sb.Append(textBox.Text); //Add the text not the textbox
sb.Append("</br>"); //Add a line break to make it look pretty
}
Label1.Text = sb.ToString();
}
If I run the application with the loop my label will return blank, no
matter what I fill out. The label is currently in the 3rd step
<asp:WizardStep ID="WizardStep3" runat="server" AllowReturn="false"
Title="Step 3" StepType="Complete">
<asp:Label ID="Label1" runat="server" Text="This text will display
when I run the application without the foreach loop"></asp:Label>
</asp:WizardStep>