Failed to use Captcha in YUM[Yii user Managment] in the registration module

[GATETE Elie MAGAMBO]

Hello,

I ve been trying to use captcha on the registration form,the code seems to be fine in the Controller,as it looks the same as the one one that are in SiteController 

that is generated by Yii on on app creation,I think the model is fine since all the rules are the same as those in the ConcactForm,

The view also seems to be correct since when i click on the link of generation a new code,it does refresh through firebug,

i can see that the code changes when i click on the link but the image cant be displayed.

When i change the action of the widget to point to site/captcha,the image appears.I ve even tried using another extension(Yii captchaextended) 

but it seems that same thing is occuring,code can change but the image is not show.

here is my code on stackoverflow,i will appreciate any help of you.

Regards;

Elie