VB confused by if path - vb.net

Question

I have VB program which user is to enter grades into using an InputBox. Regardless of user input, a message box (msgbox) stating "Please enter a number" appears. How do I change this to only show this message if a number is not entered?
Option Strict Off
Public Class Form1
Dim totalpointsaccumultator As Object
Private Sub exitButton_Click(sender As Object, e As EventArgs) Handles exitButton.Click
Me.Close()
End Sub
Public Sub assignButton_Click(sender As Object, e As EventArgs) Handles assignButton.Click
Dim inputProjectPoints, inputTestPoints As String
Dim grade, projectpoints, testpoints As String
Dim projectcounter As Integer = 1
Dim testcounter As Integer = 1
Dim isconverted As Boolean
Dim totalpointsaccumulator As Integer
Do While projectcounter < 5
inputProjectPoints = InputBox("Enter the points earned on project " & projectcounter, "Grade Calculator", "0")
inputProjectPoints = projectpoints
isconverted = Integer.TryParse(inputProjectPoints, CInt(projectpoints))
If isconverted Then
totalpointsaccumultator = totalpointsaccumulator + projectpoints
projectcounter = projectcounter + 1
Else
MessageBox.Show("Please enter a number.", "Grade Calculator", MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
Loop
Do While testcounter < 3
inputTestPoints = InputBox("Enter the points earned on test " & testcounter, "Grade Calculator", "0")
isconverted = Integer.TryParse(inputTestPoints, testpoints)
If isconverted Then
testcounter = testcounter + 1
totalpointsaccumulator = CInt(totalpointsaccumulator + testpoints)
Else
MessageBox.Show("Please enter a number.", "Grade calculator", MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
Loop
' assign grade
Select Case totalpointsaccumulator
Case Is >= 360
grade = "A"
Case Is >= 320
grade = "B"
Case Is >= 280
grade = "C"
Case Is >= 240
grade = "D"
Case Else
grade = "F"
End Select
totalpointsLabel.Text = Convert.ToString(totalpointsaccumulator)
gradeLabel.Text = grade
End Sub
End Class

Answer 1

isconverted = Integer.TryParse(inputProjectPoints, CInt(projectpoints))
should be:
isconverted = Integer.TryParse(inputProjectPoints, projectpoints)
as well as:
Dim grade, projectpoints, testpoints As String
Should be:
Dim grade as String
Dim projectpoints, testpoints As Integer
You can't pass a reference variable as a different type by trying to convert/cast it, that just returns the value in the type you requested (if possible, which is ironic considering you're use of Integer.TryParse()) it doesn't actually change the underlying type of the variable you declared.
Because of this issue, your Integer.TryParse() always fails, meaning isconverted is always false and you'll always get the message box.
Edit: Forgot to add, Plutonix is right. Set Option Strict ON!!