Hi Xu, sorry to hear that there are some problems working with the Google Page Speed widget and our team will do everything we can to help.
I have reached out to our W3TC support team about this issue and I will let you know as soon as I hear back from them.
Alternatively, you can create a post in the W3TC Support forums to contact them directly if you would prefer.
Thank you for your patience while our team works to get this sorted out for you.