I'm assuming you're using the just released 2.0.1 version. If you create a target called "target-1" in the UI, what you need to do is make sure that the target you start on the RPi is also called "target-1" because by default it will be called "defaultTargetID". You can specify the name as a command line parameter. You probably also need to specify the location of the server (which defaults to localhost):
java -Dagent.identification.agentid=target-1 -Dagent.discovery.serverurls=http://your.ace.host:8080 -jar target.jar
If you want to learn more about running a target and what you can configure, I highly recommend checking out this page/section:
http://ace.apache.org/user-doc/user-guide.html#running-a-target