Gtk# TextView and Scrolling Text

Hi there,
I'm fighting with TextView widget. Everything is fine except that when I load text to it and move cursor in it - the coursor can go out of view (TextView doesn't scroll). I tried many examples with using TextIter and TextMark and ScrollToMark function, bu it simply doesn't work.
Can anyone please tell me what am I doing wrong?

--
Best regards,
Emfor