ช่วยหน่อยนะค๊าโพสไปแล้วแต่ไม่มีคนตอบเลยจะส่งแล้วขอคำชี้แนะด้วยค่ะมือใหม่อ่อนอยู่ค่ะ โค้ด vb ค่ะ

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim DateBirth As Date = date_birthday.Text
        Dim DateCalc As Date = date_now.Text

        Dim DateTemp As Date

        Dim d, m, y As Integer

        If DateBirth > DateCalc Then

            MessageBox.Show("", "", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End If

        '//-- คำนวณหาปี

        y = DateCalc.Year - DateBirth.Year

        DateTemp = DateAdd(DateInterval.Year, y, DateBirth)

        y = y + (DateTemp > DateCalc)

        '//-- คำนวณหาเดือน

        DateBirth = DateAdd(DateInterval.Year, y, DateBirth)

        m = DateDiff(DateInterval.Month, DateBirth, DateCalc)

        m = m + (DateAdd(DateInterval.Month, m, DateBirth) > DateCalc)

        '//-- คำนวณหาวัน

        DateBirth = DateAdd(DateInterval.Month, m, DateBirth)

        d = DateDiff(DateInterval.Day, DateBirth, DateCalc)

        d = d + (DateAdd(DateInterval.Day, d, DateBirth) > DateCalc)

        TextBox1.Text = "อายุตอนนี้  :  " & y & " ปี " & m & " เดือน " & d & " วัน "


        Dim d4 As Date = CDate(date_birthday.Text)
        d4 = d4.AddYears(60)
        date_retire.Text = CStr(d4)



        Dim Year1 As Integer
        Dim Month1 As Integer
        Dim Day1 As Integer
        Dim Date3 As Date

        Dim dYear1 As String
        Dim dMonth1 As String
        Dim dDay1 As String

        Year1 = DateDiff("yyyy", date_now.Text, date_retire.Text)
        Date3 = DateAdd("yyyy", Year1, date_now.Text)
        If Date3 > date_retire.Text Then
            Date3 = DateAdd("yyyy", -1, Date3)
            Year1 = Year1 - 1
        End If
        Month1 = DateDiff("m", Date3, date_retire.Text)
        Date3 = DateAdd("m", Month1, Date3)
        If Date3 > date_retire.Text Then
            Date3 = DateAdd("m", -1, Date3)
            Month1 = Month1 - 1
        End If
        Day1 = DateDiff("d", Date3, date_retire.Text)

        If Year1 = 0 Then
            dYear1 = ""
        Else
            dYear1 = Year1 & " ปี "
        End If
        If Month1 = 0 Then
            dMonth1 = ""
        Else
            dMonth1 = Month1 & " เดือน "
        End If
        If Day1 = 0 Then
            dDay1 = ""
        Else
            dDay1 = Day1 & " วัน"
        End If

        TextBox2.Text = "เหลืออีก  :  " & dDay1 & dMonth1 & dYear1


    End Sub