VB 2008 tugas membuat program perhitungan nilai

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles MyBase.Load        Npm.Items.Add("12110767")        Npm.Items.Add("12116512")        Npm.Items.Add("12110708")        K_dosen.Items.Add("MS4303")        K_dosen.Items.Add("YH4306")        K_dosen.Items.Add("TL4303")        K_dosen.Items.Add("MS4305")        K_dosen.Items.Add("MP4302")        K_dosen.Items.Add("P4302")
        K_Mkuliah.Items.Add("KKTI4303")
        K_Mkuliah.Items.Add("KBTI4306")
        K_Mkuliah.Items.Add("KBTI4303")
        K_Mkuliah.Items.Add("KBTI4305")
        K_Mkuliah.Items.Add("KKTI4302")
        K_Mkuliah.Items.Add("KBTI4302")
        K_Mkuliah.Items.Add("KKTI4301")
        Dim x As Integer
        For x = 100 To 1 Step -1
            NK.Items.Add(x)
            NT.Items.Add(x)
            NU.Items.Add(x)
            NUAS.Items.Add(x)
        Next x
    End Sub
    Private Sub Npm_SelectedIndexChanged(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) HandlesNpm.SelectedIndexChanged
        Select Case Npm.Text
            Case "12111049"
                Nama.Text = "KAMORIUS"
                Jurusan.Text = "Teknik Informatika"
            Case "12116512"
                Nama.Text = "Siti arbayah"
                Jurusan.Text = "Sistem informasi"
            Case "12110708"
                Nama.Text = "Annisa chairani"
                Jurusan.Text = "Akuntasi"
        End Select
        Dim x As String
        x = Microsoft.VisualBasic.Left(Npm.Text, 2)
        If Npm.Text = "12110767" Then
            Jenjang.Text = "S1"
        ElseIf Npm.Text = "12116512" Then
            Jenjang.Text = "D111"
        ElseIf Npm.Text = "12110708" Then
            Jenjang.Text = "S1"
        End If
    End Sub
    Private Sub K_dosen_SelectedIndexChanged(ByVal senderAs System.Object, ByVal e As System.EventArgs) HandlesK_dosen.SelectedIndexChanged
        Select Case K_dosen.Text
            Case "MS4303"
                N_dosen.Text = "Marzuki sinambela s.kom,M.T"
            Case "YH4306"
                N_dosen.Text = "Yasir Hasan s.kom"
            Case "TL4304"
                N_dosen.Text = "Tonni limbong s.kom,m.kom"
            Case "MS4305"
                N_dosen.Text = "Mesran m.kom"
            Case "MP4302"
                N_dosen.Text = "Megaria purba S.Si,m.kom"
            Case "PI4302"
                N_dosen.Text = "Pristiwanto s.kom"
            Case "PT4301"
                N_dosen.Text = "Pilipus Tarigan S.T,M.kom"
        End Select
    End Sub
    Private Sub Kodemkuliah_SelectedIndexChanged(ByValsender As System.Object, ByVal e As System.EventArgs)Handles K_Mkuliah.SelectedIndexChanged
        Select Case K_Mkuliah.Text
            Case "KKTI4303"
                MK.Text = "Struktur data"
            Case "KBTI4306"
                MK.Text = "Sistem Operasi"
            Case "KBTI4303"
                MK.Text = "Sistem basis data"
            Case "KBTI4305"
                MK.Text = "Pemograman visual"
            Case "KKTI4302"
                MK.Text = "Matriks dan Linier"
            Case "KBTI4302"
                MK.Text = "Komunikasi data"
            Case "KKTI4301"
                MK.Text = "Arsitektur dan Organisasi"
        End Select
    End Sub
    Private Sub Btnproses_Click(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) HandlesBtnproses.Click
        NA.Text = 0.1 * NK.Text + 0.15 * NT.Text + 0.35 * NU.Text + 0.45 * NUAS.Text
        If NA.Text >= 50 Then
            Keterangan.Text = "LULUS"
        Else
            Keterangan.Text = "GAGAL"
        End If
        If NA.Text >= 80 Then
            NH.Text = "A"
        ElseIf NA.Text >= 70 Then
            NH.Text = "B"
        ElseIf NA.Text >= 60 Then
            NH.Text = "C"
        ElseIf NA.Text >= 50 Then
            NH.Text = "D"
        Else
            NH.Text = "E"
        End If
    End Sub
    Private Sub Btnkeluar_Click(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) HandlesBtnkeluar.Click
        Close()

    End Sub


  
    Private Sub Btnhapus_Click(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) HandlesBtnhapus.Click
        Npm.Text = ""
        Nama.Text = ""
        Jenjang.Text = ""
        Jurusan.Text = ""
        K_dosen.Text = ""
        N_dosen.Text = ""
        K_Mkuliah.Text = ""
        MK.Text = ""
        NK.Text = ""
        NT.Text = ""
        NU.Text = ""
        NUAS.Text = ""
        NA.Text = ""
        NH.Text = ""
        Keterangan.Text = ""
    End Sub
    Private Sub Jurusan_TextChanged(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) HandlesJurusan.TextChanged
    End Sub
End Class

        K_dosen.Items.Add("PT4301")