reg:Captcha Image not displaying in portal as well as in wdabap

Hi All

I have followed the below link

http://scn.sap.com/thread/3373177

in that I was provided with code and process of how to generate the captcha image.

I followed the same but in my application I am unable to view the captcha image .

please find the screen shot .

can you please let me know why image is not getting displayed .

awaiting for reply

Thanks & Regards

Deepika.M