Unable to add an Image to a powerpoint presentation.

Hi,

I am using the following code to add a new slide to a ppt file and add an image. I am using Open XML 2.5 SDK.

A new slide is getting added but not the image. Is there anything wrong in this code?

int position = 1;
            using (PresentationDocument presentationDocument = PresentationDocument.Open("c.pptx", true))
            {

                PresentationPart presentationPart = presentationDocument.PresentationPart;

                Slide slide = new Slide(new CommonSlideData(new ShapeTree()));
   
                NonVisualGroupShapeProperties nonVisualProperties = slide.CommonSlideData.ShapeTree.AppendChild(new NonVisualGroupShapeProperties());
                nonVisualProperties.NonVisualDrawingProperties = new NonVisualDrawingProperties() { Id = 1, Name = "" };
                nonVisualProperties.NonVisualGroupShapeDrawingProperties = new NonVisualGroupShapeDrawingProperties();
                nonVisualProperties.ApplicationNonVisualDrawingProperties = new ApplicationNonVisualDrawingProperties();

                // Specify the group shape properties of the new slide.
                slide.CommonSlideData.ShapeTree.AppendChild(new GroupShapeProperties());

                // Create the slide part for the new slide.
                SlidePart slidePart = presentationPart.AddNewPart<SlidePart>();


                // Save the new slide part.
                slide.Save(slidePart);
                string imgId = "rId" + new Random().Next(2000).ToString();
                ImagePart imagePart = slidePart.AddImagePart(ImagePartType.Png, imgId); 

                using (FileStream stream = new FileStream("a.png", FileMode.Open))
                {
                    stream.Position = 0;
                    imagePart.FeedData(stream);
                }

                

                slide.Save(slidePart);
                



                

                // Modify the slide ID list in the presentation part.
                // The slide ID list should not be null.
                SlideIdList slideIdList = presentationPart.Presentation.SlideIdList;

                // Find the highest slide ID in the current list.
                uint maxSlideId = 1;
                SlideId prevSlideId = null;

                foreach (SlideId slideId in slideIdList.ChildElements)
                {
                    if (slideId.Id > maxSlideId)
                    {
                        maxSlideId = slideId.Id;
                    }

                    position--;
                    if (position == 0)
                    {
                        prevSlideId = slideId;
                    }

                }

                maxSlideId++;

                // Get the ID of the previous slide.
                SlidePart lastSlidePart;

                if (prevSlideId != null)
                {
                    lastSlidePart = (SlidePart)presentationPart.GetPartById(prevSlideId.RelationshipId);
                }
                else
                {
                    lastSlidePart = (SlidePart)presentationPart.GetPartById(((SlideId)(slideIdList.ChildElements[0])).RelationshipId);
                }


                // Use the same slide layout as that of the previous slide.
                if (null != lastSlidePart.SlideLayoutPart)
                {
                    slidePart.AddPart(lastSlidePart.SlideLayoutPart);
                }

                // Insert the new slide into the slide list after the previous slide.
                SlideId newSlideId = slideIdList.InsertAfter(new SlideId(), prevSlideId);
                newSlideId.Id = maxSlideId;
                newSlideId.RelationshipId = presentationPart.GetIdOfPart(slidePart);

                // Save the modified prsentation.
                presentationPart.Presentation.Save();

Thanks in advance.