Thanks for your remind jodev . I think I forgot to add access rules. But I solved this in a much more complicated way. I want to customize my captcha and I found captcha,both mine and Yii’s, cannot be rendered inside the framework anyway (Maybe because of the access rules you remind me). So I have to put it outside the framework in the root file, problem is, in this way, it cannot share sessions with Yii, so i can’t pass the captcha result to validate. I use cache to solve it. Well… whatever, I’ve solved it though in an inefficient way. And i don’t want to entangle on this issue anymore. I’ve wasted 3 days on this. Really tired about it .
Thank you again. I’ll try your solution if i want to use Yii’s captcha someday.