Live-Chat not working after changing language

Hi all, i have one problem..

When clicking on "Live-Chat" at the bottom of website, the popup window for Live-Chat opens. When changing the language in this popup from English to German or Turkish it stops working. The popup is blank then and even trying to open Live-Chat again no matter what language, the popup remains blank.
The problem is only in internal network, from outside ( client ) working all good...

can someone help me?

Thanks in advance