VB.Net "Convertion of the string into the type double is not valid" : Guys, I need some help with a VB.Net code, I can´t go through
Every time I run it I get the message "THe convertion of the string is not valid for double, can you help me with that. thanks
        Dim num1 As Double = 0
        Dim num2 As Double = 0
        Dim operacion As Decimal
        ' Asignar n valores a las variables declaradas
        num1 = TextBox1.Text
        num2 = TextBox2.Text
        ' Operacion de incremento porcentual
        operacion = num1 + num1 * num2 / 100
        ' Mostrar el resultado de la operacion mediante un MsgBox - Se redondea el resultado
        MsgBox(Math.Round(operacion, 2), MsgBoxStyle.OkOnly, "Incremento Porcentual")
    End Sub