Attaching an image to a node - version 7

I’m migrating code from version 5 to version 7 and am having trouble with uploading an image. The page allows a user to choose an image and then when the form is submitted it uploads this image into a sub folder as a new node.

The code I have is as follows:

public static bool AddImageToNode(UserInfo user, int nodeId, string newNodeName, System.Web.HttpPostedFile postedFile) { bool fileAdded = false;

    TreeProvider tree = new TreeProvider(user);
    CMS.DocumentEngine.TreeNode fundraisingPageNode = DocumentHelper.GetDocument(nodeId, defaultCulture, tree);

    if (fundraisingPageNode != null)
    {
        CMS.DocumentEngine.TreeNode imagesFolderNode = tree.SelectSingleNode(siteName, fundraisingPageNode.NodeAliasPath + "/Images", defaultCulture, true, "CMS.Folder", false);

        if (imagesFolderNode != null)
        {
            //add file document
            CMS.DocumentEngine.TreeNode fileNode = CMS.DocumentEngine.TreeNode.New("CMS.File", tree);
            fileNode.NodeAlias = newNodeName;
            fileNode.NodeName = newNodeName;
            fileNode.SetValue("FileName", postedFile.FileName);
            fileNode.DocumentCulture = defaultCulture;

            fileNode.Insert(imagesFolderNode.NodeID);

            if (fileNode.NodeID > 0)
            {
                //add attachment
                AttachmentManager am = new AttachmentManager();


                // Create the attachment and resize it
                Guid attachmentGuid = Guid.NewGuid();
                AttachmentInfo ai = new AttachmentInfo(postedFile, fileNode.DocumentID, attachmentGuid);

                System.IO.MemoryStream msIn = new System.IO.MemoryStream(ai.AttachmentBinary);
                System.IO.MemoryStream msOut = new System.IO.MemoryStream(ai.AttachmentBinary);
                System.Drawing.Image img = System.Drawing.Image.FromStream(msIn);

                img.Save(msOut, System.Drawing.Imaging.ImageFormat.Jpeg);
                ai.AttachmentBinary = msOut.ToArray();
                am.SetAttachmentInfo(ai);

                // Set the attachment reference
                fileNode.SetValue("FileAttachment", attachmentGuid);
                fileNode.Update();
            }
        }
    }

I end up with what looks like the image but there doesn’t appear to be any file attached so nothing displays. Is there something I’m not doing right?