If you have ever tried to use the MapResourceManager on a page without a Map Control or use the functionalities directly through the ResourceItems on the MapResourceManager, you must have found that the functionalities do not work as expected. The reason the functionalities do not work as expected is because the resources underlying the resource items should be initialized before use. Reading over the ESRI’s .NET ADF library, there are 2 methods that suggest that they will accomplish the task of initializing the resource, the Initialize method on the IGISResource interface and the InitializeResource method on the GISResourceItem.
But the Initialize method on the IGISResource interface does not do the job right. In order to initialize the resource right use the InitializeResource method on the GISResourceItem. This is not documented anywhere as far as I know. So, if the Query method on the IQueryFunctionality interface returns null for no reason when you expect results, trying initializing the resource using the InitializeResource method on the GISResourceItem.
Update: Heard from some ESRI folks on this issue. IGISResource.Initialize() initializes the resource only. IGISResourceItem.InitializeResource() initializes both the resource and the datasource of the resource. Always to use InitiializeResource(), since there are more logic here for handling initialization errors, validation stuff etc, whereas, with Initialize() it’s dependent on the individual resource’s implementation.