When doing AMF projects especially in AIR it’s good to see what gets returned from your Zend_AMF services, here is the solution; ZamfBrowser allows developers to unit test ZendAMF Service classes via an Adobe AIR application. Implementation requires a simple edit to the ZendAMF gateway file that allows ZamfBrowser to introspect your server set up and provide access for all classes and methods registered with the Zend_Amf_Server object. For version 1.0 the ZamfBrowser AIR source code is still closed, but it is intended to go Open Source as soon as the source code documentation is complete and a couple of features are implemented that are still in the pipeline.
Go and get it: http://www.zamfbrowser.org/