[turba] empty page

[Jan Kolar]

Hello,
I have installed Turba in order to have in Imp an addressbook available.
   Imp with Horde works fine. However, when I click on Addressbook icon
in Imp I obtain just blank page with

Warning: Cannot add header information - headers already sent by (output
started at /data/htdocs/imp/horde/turba/index.php:19) in
/data/htdocs/imp/horde/turba/index.php on line 29

Could anybody give me an advice how to track down an error. Thank you.

Jan Kolar