How can I save a group of Direct2D bitmaps to a dynamic image file?

Question

recently, I'm disturbed by saving bitmap to dynamic image file. I want to turn a group of bitmaps into a dynamic image file, but the function IWICBitmapFrameEncode::WriteSource only cover the previous frame while writing a new frame to file, and it makes the image file failed (the file is a static image). How can I solve the problem?

In addition, perhaps I haven't explained clearly , the following photo will help you understand:

the example of "dynamic image file", result of Program output. this image is dynamic and multiframe (GIF)

the example of "static image", the Direct2D Bitmap which has been read into the memory of application. this image is singleframe (JPEG)