How can I ensure that a user does not leave any multiple choice inputs unselected?

I'm trying to do a hotel billing system wherein the user cannot leave combo boxes, radio buttons and list boxes not selected and i'm out of ideas can someone help me with this?

-newbie

Dim inp As Integer = 0

If RadioButton1.Checked Or RadioButton2.Checked Or RadioButton2.Checked = False Then
    inp = 1
ElseIf ComboBox1.Text = "" Then
    inp = 1
ElseIf ListBox1.SelectedIndex() Then
    inp = 1
End If

If inp = 1 Then
    MessageBox.Show("No selected type of payment" & vbCrLf & "Or" & vbCrLf & "No selected room capacity" & vbCrLf & "Or" & vbCrLf & "No selected room type", "Error")
    inp = inp = 1
    RadioButton1.Checked = False
    RadioButton2.Checked = False
    RadioButton3.Checked = False
    ListBox1.ClearSelected()
    ComboBox1.Text = ""
End If