Why do I keep getting this error? VB 2010 Express

Question

This is what I have, but I get an error when I try debugging this and then it highlights bmp.Save(sPath) in yellow as if it doesn't know what I'm talking about, if someone could come up with a solution to my problem, and maybe some organization tips, that would be great ;)

Public Class Form1

    Private Function MakeName(ByVal Pathname As String, ByVal Count As Integer) As String

        Return System.IO.Path.Combine(Pathname, "ss" & Count.ToString & ".bmp")

    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Me.Opacity = 0

        If My.Computer.FileSystem.FileExists("C:\cache") Then

        Else

            My.Computer.FileSystem.CreateDirectory("C:\cache")

        End If

        Dim SaveCount As Integer = 0

        Dim sPath As String

        Dim bmp As Bitmap

        Timer1.Enabled = True

        Do

            sPath = MakeName("C:\cache", SaveCount)

            SaveCount += 1

        Loop Until Not System.IO.File.Exists(sPath)

        bmp = CType(PictureBox1.Image, Bitmap)

        bmp.Save(sPath)

    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

        Dim bounds As Rectangle

        Dim screenshot As System.Drawing.Bitmap

        Dim graph As Graphics

        bounds = Screen.PrimaryScreen.Bounds

        screenshot = New System.Drawing.Bitmap(bounds.Width, bounds.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb)

        graph = Graphics.FromImage(screenshot)

        graph.CopyFromScreen(bounds.X, bounds.Y, 0, 0, bounds.Size, CopyPixelOperation.SourceCopy)

        PictureBox1.Image = screenshot

        Timer1.Enabled = False

        Me.Opacity = 100

    End Sub

End Class

I tried to start debugging, I clicked button1 and it highlighted bmp.Save(sPath) and said:

NullReferenceException was unhandled

Object reference not set to an instance of an object.

Answer 1

"I get an error"  What does this mean? What if you continue pressing the shortcut for single-step?

BTW, you should dispose the Graphics object after usage. And I suggest to directly call IO.Directory.Create.

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Armin

Answer 2

"I get an error"  What does this mean? What if you continue pressing the shortcut for single-step?

BTW, you should dispose the Graphics object after usage. And I suggest to directly call IO.Directory.Create.

---

Armin

I've changed my post a little, it should be easier to understand what "error" I'm getting.

Answer 3

Thx for clarifying.

Probably the timer hasn't ticked yet and there's no image in the picturebox. Is that right? If so, set the button's enabled property to false in the designer and set it to true at run-time in the timer's tick event.

EDIT: I just see "Timer1.Enabled = True" in the button click event. The timer won't tick before the click event handler has exitted. Why don't you start the timer before?

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Armin