pick: That error means either: 1) aMule wasn't running when you tried to run amuleweb, or 2) amuleweb is trying to connect to aMule using a different port number than aMule is accepting connections on.
Go into aMule's preferences. In "Remote Controls", enable "Accept external connections" and specify a password in the field below (this is the password that amuleweb uses to authenticate to aMule and is different than the password that you use to login to amuleweb using your browser).
When aMule runs amuleweb for you, amuleweb gets its configuration settings from amule.conf. When you run amuleweb manually via terminal, it gets its configuration settings from remote.conf. Because of this, the two methods can have different results. The easiest way to overcome this is to set everything the way you want it in aMule, which writes amule.conf. Then, run this command in the terminal:
amuleweb --create-config-from=~/Library/Application\ Support/aMule/amule.conf
which creates remote.conf based off of the settings in amule.conf.
Now that you know they both agree, please try your test again.