AutoCAD Inventor :: Saving Image From Picturebox

I get an image from the camera object using apprentice and putting it into a Picturebox. But when I try and save the image using the standard Picturebox.image.save method I get an error.

Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        Dim oApprentice As New Inventor.ApprenticeServerComponent
        Dim Doc As Inventor.ApprenticeServerDocument
        Doc = oApprentice.Open(oApp.ActiveDocument.FullFileName) 'oApp is defined elsewhere.
        ' Create a client view for the document, passing in the hWnd for a picture box.  
        Dim clientView As Inventor.ClientView = Doc.ClientViews.Add(PictureBox1.Handle)
[code]....