How to bind *.png image in crystal report dynamically

Question

Hi am working in crystal reports. In that report I want to bind a png image dynamically. But i couldn't bind it. Because the background of the png image turned into black color. I referred many sites but they mentioned that to convert the png image into wmf format and attach one word file into crystal report and paste that wmf code on that file. After execution of that crystal report the word file content like the words only show but not the image. so Kindly help me regarding this issue. Thanks in advance.