Its a tad difficult to explain whats going wrong, heres my new code(only a couple small changes), would you possibly be able to tell me what is incorrect please

? its not runnig correctly the numbers coem out wrong.
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
Dim strMath As String
Dim intLow As Integer
Dim intHigh As Integer
Dim intNumProb As Integer
Dim rndGenerator As New Random
Dim intNum As Integer
Dim intNum2 As Integer
'Declare variables
strMath = txtMath.ToString
intLow = Convert.ToInt32(txtLow.Text)
intHigh = Convert.ToInt32(txtHigh.Text)
intNumProb = Convert.ToInt32(txtNumProb.Text)
intNum = rndGenerator.Next(intLow, intHigh)
intNum2 = rndGenerator.Next(intLow, intHigh)
'Assing values to variables
If intNumProb < 1 Or intNumProb > 20 Or Not IsNumeric(intNumProb) Then
MessageBox.Show(" Data must be a number between 1 and 20")
End If
If Not IsNumeric(intLow) Then
MessageBox.Show("Data must be numeric")
End If
If Not IsNumeric(intHigh) Then
MessageBox.Show(" Data must be numeric")
End If
Select Case strMath
Case "A"
InputBox(Convert.ToString(intNum + intNum2))
Case "M"
InputBox(Convert.ToString(intNum * intNum2))
Case "S"
InputBox(Convert.ToString(intNum - intNum2))
Case Else
MessageBox.Show("Value must be A,S or M")
End Select
End Sub
End Class