The next trouble with Tree View

Could you help me to fix the next trouble?
SilverStripe works perfectly on localhost but there is a strange thing with Tree View on the hosting.
When I click on some page within TreeView then a revolving circle and a caption 'Loading' emerge,
a few secs later the caption vanishes but the circle rotates so far and there is no transition to clicked page,
it can last for ever. All other ajax things work fine. What is it?
Thank you.

I have found the the following:
if I type http://example.com/ss/admin/show/1 or http://example.com/ss/admin/show/2 then starts page editing
but if I click on a page icon inside Tree View nothing happens.