There is a blank window poping up when I click the button of Maths Editor.
How can I fix it?
Can anbody help me?
The maths editors uses mathjax which is hosted on a CDN but it looks like the network you are on does not have access to it.
Your site administrators in this case should download and install a local copy of mathjax.
Actually it looks like you are using wiris instead of the default maths plugins - but it looks like you have a similar problem with your network.
WIRIS is a commercial product that requires a license subscription on a production site. It is possible that the account is expired. I see a 403 Forbidden error in error listing. You should probably contact WIRIS directly for licensing or help configuring the setup.