Clear Form Button is not working correctly - asp.net

Question

Created a master.page and added several content pages. Imported the code from previous webform into one of my content pages. Now the clear button is not working correctly. It will not clear the textboxes or checkboxes. greatly appreciate any help. The form worked perfectly as a standalone page.
vb code:
Partial Class _Default
Inherits System.Web.UI.Page
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim Num1, Num2, Num3, Num4 As Double
Dim Opt1, Opt2, Opt3, Opt4 As Double
Dim BaseTotal, OptionTotal, GrandTotal, Tax As Double
Num1 = Val(TextBox1.Text) * 1500
Num2 = Val(TextBox2.Text) * 70
Num3 = Val(TextBox3.Text) * 90
Num4 = Val(TextBox4.Text) * 130
If CheckBox1.Checked Then
Opt1 = 175
End If
If CheckBox2.Checked Then
Opt2 = 400
End If
If CheckBox3.Checked Then
Opt3 = 100
End If
If CheckBox4.Checked Then
Opt4 = 200
End If
' sum of checkboxes
OptionTotal = Opt1 + Opt2 + Opt3 + Opt4
'total base options
BaseTotal = Num1 + Num2 + Num3 + Num4
' Tax calculation
Tax = (OptionTotal + BaseTotal) * 0.095
GrandTotal = (BaseTotal + OptionTotal + Tax)
'output to text boxes
TextBox5.Text = FormatNumber(BaseTotal, 2)
TextBox6.Text = FormatNumber(OptionTotal, 2)
TextBox7.Text = FormatNumber(Tax, 2)
TextBox8.Text = FormatNumber(GrandTotal, 2)
End Sub
For Each ctrl As Control In form1.Controls
If ctrl.[GetType]() = GetType(TextBox) Then
DirectCast(ctrl, TextBox).Text = String.Empty
ElseIf ctrl.[GetType]() = GetType(CheckBox) Then
DirectCast(ctrl, CheckBox).Checked = False
End If
Next
***************If I use the following code of course it works, however it would be tedious if there were numerous controls on the page.
Protected Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
TextBox1.Text = ""
TextBox2.Text = ""
TextBox3.Text = ""
TextBox4.Text = ""
TextBox5.Text = ""
TextBox6.Text = ""
TextBox7.Text = ""
TextBox8.Text = ""
CheckBox1.Checked = False
CheckBox2.Checked = False
CheckBox3.Checked = False
CheckBox4.Checked = False
End Sub