[RESOLVED] Listbox and counter errors...

[ItsBryanTho]

So my program is suposed to prompt me for 5 integers. these 5 will be added together and produce an average I also need to put a Letter grade, in a label for the average of the 5 numbers.(this idk how to do)
these 5 must be between 0-100 and I'm just lost...i built a program like this before with weight loss but I'm aslo smashed with python can you guys help me out with where some errors are? I'm just crammed and i keep confusing the 2 languages that i'm just now learning.

'Program Name: Grade Book
'Dev: Bryan Cruse
'Date:11/24/15

Option Strict On




Public Class frmGradeBook
    Dim intGrades As Integer
    Dim IntNumberOFentries As Integer = 1
    Dim StrGrades As String
    Dim decFinalGrades As Decimal
    Dim intMaxNumberOfEntries As Integer = 5
    Dim StrInputMessage As String = "Please enter your grade"
    Dim StrInputHeading As String = "Grade Book"
    Dim StrNormalMessage As String



    Private Sub mnuExitProgramItem_Click(sender As Object, e As EventArgs) Handles mnuExitProgramItem.Click
        Close()
    End Sub

    Private Sub mnuClearGradesItem_Click(sender As Object, e As EventArgs) Handles mnuClearGradesItem.Click
        lstGrades.Items.Clear()

    End Sub

    Private Sub btnEnterGrades_Click(sender As Object, e As EventArgs) Handles btnEnterGrades.Click

        Dim strCancelClicked As String = ""
        StrGrades = InputBox("Please Enter your grades", "Grade Book", )


        Do Until IntNumberOFentries > intMaxNumberOfEntries Or StrGrades = strCancelClicked


          

            If IsNumeric(StrGrades) Then
                intGrades = CInt(Convert.ToDecimal(StrGrades))

                If intGrades > 100 Then
                    MsgBox("Please enter a valid grade.", MsgBoxStyle.Exclamation, "Grade Book")
                    If intGrades > 0 Then
                    Else : MsgBox("You entered a non usable number", , "Input Error")
                    End If
                    lstGrades.Items.Add(intGrades)
                    decFinalGrades += intGrades
                    IntNumberOFentries += 1
                    StrInputMessage = strNormalMessage
                    If IntNumberOFentries >= intMaxNumberOfEntries Then
                        StrGrades = InputBox(StrInputHeading & IntNumberOFentries, StrInputHeading, " ")
                    End If
                End If
            End If
        Loop

        lstGrades.Items.Add(intGrades)

        If IntNumberOFentries <= 5 Then
            lblScore.Visible = True
            decFinalGrades = CDec(intGrades / 7)
            If decFinalGrades <= 68 Then
                lblGrade.Text = "F"
            End If
        End If

            End While


    End Sub
End Class