The NetConnection Debugger is an old utility from the early days of Flash Remoting that some developers still find useful. It has an issue, however, displaying types that have been registered with Object.registerClass(). If your Flex server is installed locally, we suggest enabling server-side "debug" level logging in /WEB-INF/flex/gateway-config.xml to watch the raw trace information in the Flex server console/logs from the AMF Gateway as it processes your RemoteObject requests.

Flex Builder also includes a Network Debugger that allows you to monitor AMF traffic.