I have finally found the problem.
It's all about recaptcha. Because my network here can not access the recaptcha website directly, I just can not see the identifying code in the step2.
Today, I just tried with a proxy and I created it successfully.
I'm sorry to bother you. Thank you very much for you help.
And finally I suggest that you can make a hint or sign to tell that there is a identifying code from recaptcha.com website. That would be much help.
Thank you again.