I am creating a cash register app. When the total button is hit, the subtotal, tax, and total is displayed in textboxes. I have this code for the total box. When I run it, I get an I get an InvalidCastException. Says that the conversion from string 'textbox' to type 'double' is not valid? Can anyone help? VISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASE Private Sub TextBox_tax_TextChanged(sender As Object, e As EventArgs) Handles taxBox.TextChanged If taxBox.Text.Length <> 0 Then Dim subtot As Double = subtotalBox.Text Dim tax As Double = taxBox.Text Dim taxamt As Double taxamt = (subtot * tax) / 100 Dim tot As Double tot = subtot + taxamt totalBox.Text = tot Else totalBox.Text = "" End If End Sub VISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASEVISUAL BASIC PLEASE VISUAL BASIC PLEASE