Hi. It sounds like maybe the AIR app isn't getting compiled against the services-config.xml file for your LCDS server. Make sure in the Flex Compiler settings for you AIR project there is a -services compiler argument that points to your services-config.xml file. This should look something like. . .
-services <path-to-lcds-webapp>\WEB-INF\flex\services-config.xml
If that's not the issue follow the steps to debug the problem as Bill outlined. The following section of the BlazeDS documentation has some good information which may elaborate a bit more on the steps/suggestions that Bill had for you.
http://livedocs.adobe.com/blazeds/1/blazeds_devguide/help.html?content=build_apps_6.html
-Alex