Why client shows username instead of fullname

I finished the installation of openfire / spark and the spark client always shows username (NT username) instead of user full name. Is there a configuration somewhere to force the display of user fullname instead of userid?

Thanks

Where exactly does it show username? In the contacts list or your own name on top of the Spark and in the chat window? Are you using local database or pulling your contacts from LDAP? If you just want your name to show in Spark, then go to Spark > Edit my profile and enter your name into Nickname field, then restart Spark.