I believe your local derby is not up yet. To check this, issue:
netstat -an | findstr 1527
.
See if it returns anything. If nothing is returned, try to start the Derby Network Service manually. Go to <WLS_HOME>\common\derby\bin
and click the startNetworkServer.cmd
.
Double check with netstat
again. If it's there, you can try to add to the datasource.
Note: this only covers manually start the Derby network service (not automatially start it upon weblogic start, which a bit tricky).