Connection Error....Unable To Add Contact

Hi guys,

I have a problem on Spark when an user try to add somebody is shown a message: Reconnecting…Connection error and after this is shown another message: Unable to add contact. I have already uninstall Spark on her computer e re-install, however, the same problem persist yet. Open Fire is installed on Ubuntu with their services and authenticating by AD from Windows Server 2003. I hope anybody can help me!!!