Using SearchDatastore_Task to filter a list of files

I am developing a plug-in using C#/ASPX (.Net 4.0) and vSphere 5.0.  I want to allow the user to search for files in a known location on the datastore.

I have been looking in the forums for others using SearchDatastore_Task, but I don't see anyone running into this issue.

Using the Managed Object Browser, I can get all of the files every time.  If I use the C# AppUtil class and set up my objects with the same data that I use in the Managed Object Browser, the page hangs until I see the following text within the vSphere Client:  "This program cannot display the webpage"

If I use the Visual Studio debugger, the code enters the "WaitForTask()" method and then hits a Stack Overflow Exception in the ServiceUtil.cs file ("An unhandled exception of type 'System.StackOverflowException' occurred in Vim25Service2010.XmlSerializers.dll").  Specifically in the ServiceUtil.cs file, the error occurs at the following line:

            updateset =

               _connection.Service.WaitForUpdates(

                  _connection.PropCol, version

               );

Below, I have the code that I am using for the Managed Object Browser, followed by the code that I am using for C#.  Has anyone else run into this before and/or is anyone able to see what I may have done wrong?

Note: In both examples below, the HostDatastoreBrowser is type:HostDatastoreBrowser    Value:datastoreBrowser-datastore-63

For the MOB, I use the following and get all 3 ZIP files that are in the folder:

datastorePath (required)

[vzipesxi2-local] c

searchSpec (optional)

<!-- optional -->

<searchSpec>

   <!-- optional -->

   <!-- array start -->

   <!-- optional -->

   <query>

   </query>

   <!-- array end -->

   <!-- optional -->

   <details>

      <fileType>false</fileType>

      <fileSize>true</fileSize>

      <modification>true</modification>

      <fileOwner>false</fileOwner>

   </details>

   <!-- optional -->

   <searchCaseInsensitive>true</searchCaseInsensitive>

   <!-- optional -->

   <!-- array start -->

   <!-- optional -->

   <matchPattern>*.zip</matchPattern>

   <!-- array end -->

   <!-- optional -->

   <sortFoldersFirst>false</sortFoldersFirst>

</searchSpec>

For C#, I use the following, and the last line (WaitForTask) is where the code hangs:

FileQueryFlags fqf = new FileQueryFlags();

fqf.fileOwner = false;

fqf.fileOwnerSpecified = true;

fqf.fileSize = true;

fqf.fileType = false;

fqf.modification = true;

HostDatastoreBrowserSearchSpec hdbss = new HostDatastoreBrowserSearchSpec();

hdbss.query = new FileQuery[] {new FolderFileQuery()};

hdbss.details = fqf;

hdbss.matchPattern = new string[] { "*.zip" };

hdbss.searchCaseInsensitive = true;

hdbss.searchCaseInsensitiveSpecified = true;

hdbss.sortFoldersFirst = false;

hdbss.sortFoldersFirstSpecified = true;

ServiceUtil svcUtil = vsAppUtil.getServiceUtil();

ManagedObjectReference hostDSBrowser = (ManagedObjectReference)svcUtil.GetDynamicProperty(searchDatastoreMor, "browser");

searchDatastorePath = "[vzipesxi2-local] c";

apiTaskMor = vsAppUtil._connection._service.SearchDatastore_Task(hostDSBrowser, searchDatastorePath, hdbss);

apiTaskResult = svcUtil.WaitForTask(apiTaskMor);

NOTE: In reviewing other forum posts, I saw where users where setting the hdbss.query to a new FolderFileQuery() object.  I didn't think that I needed that, but I have added it.  Since then, I get the same results.  I have left the line in here for now, but I am not sure that I need it.  Note that my Managed Object Browser does not have that value set, and it is working.