kontact <-> egroupware... how?

Hi all,


I have a working egroupware 1.6 setup, now I need to connect a kontact 4.3.2 
to it... and no matter which of the several google suggestions i try, it 
simply does not work at all. I can create calendar entries in kontact that 
fail to upload to egroupware, i can create calendar entries in egroupware that 
simply dont show up in contact.

Anyone on the list who could suggest something?
...might even accept a "scrap egroupware, use XYZ instead" solution as long as 

- it works with kontact
- it has windows clients / preferrably works with outlook


thanks in advance,

MH