Create contacts usabe in appointements

[Marcin Krzyzanowski]

I have situation where I create contact with WebDAV, this contact exists 
but in Appointements form I cannot choose this contact as a "contact" 
person, I can choose every contact created with Outlook but not created 
with WebDAV. Wha is so unique that make contacts created from Outlook 
more usable than other ?

Creatign contact as a base I took: http://support.microsoft.com/?kbid=296126