Couldn't add CardDAV-Contact to the local database

[lexusburn]

Hello,

i use the latest version of plugin 0.5.1 with roundcube 0.9.2 and an Apple CardDAV Server.
Setup works fine, but i did not get all contacts. Instead of this i found some of these lines in log:

v0.5.1 | carddav_server_id: 8 | Couldn't add CardDAV-Contact to the local database with the vCard id 1EB31C23-30BD-4CAD-9B2A-C94F02A708EC-ABSPlugin

Can you help or tell me how i can find out more about the problem?

best regards