Why doesn't this .plist work?

Question

Here she comes...

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>Titan Server</string>
    <key>ProgramArguments</key>
    <array>
        <string>/Users/Ian/Titan/bin/titan.sh</string>
        <string>start</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>WorkingDirectory</key>
    <string>/Users/Ian/Titan</string>
</dict>
</plist>

If I go into terminal and do...

launchctl load "Titan Server.plist"

... it says ...

/Library/LaunchAgents/Titan Server.plist: Operation already in progress

Huh?

If I navigate to the working directory manually and type the command it works ok.