Problem with polish letters [UTF-8]

Hello,

I'am starting with DataTables but I have big problem.
Cells containing polish letters (ó,ł,ż,ć etc.) does't display in my server-side installation. Row is ok, but cell with polish letter is empty.

Screen: http://scr.hu/0lfe/558d9

I have UTF-8 charset in MYSQL database/tables and in header.

What is wrong? What should I change?