Preview thumbnail wont update.

Question

The following is for Adobe Illustrator CS4 SDK on a MAC.
In the  following code.  I export a document with multiple layers as an AI  file.  Then I delete a layer and export the document again under a new  name.
In the example below the first file is called OriginalFile and the  second is called DeletedLayerFile.  In the OriginalFile the preview  image that is displayed in the Finder of OSX matches the actual contents  of the file.  In DeletedLayerFile the preview image will show a  thumbnail of OriginalFile but the actual contents of the file will be  different (they have a deleted layer).  I cannot figure out why the  preview image persists across these edited files. And ideas?!?
ASErr PlayNativeExport(SPBasicSuite *basic,char* newName);
void  Example()
   AILayerHandle tempLayer;
    PlayNativeExport(message->d.basic, "OriginalFile");               //export the original file
    sAILayers->GetNthLayer(0,&tempLayer);                                 //get the top  layer
    sAILayers->DeleteLayer(tempLayer);                                       //delete the top layer
    PlayNativeExport(message->d.basic,"DeletedLayerFile");       //export the file without the top layer (preview image shows top layer still there!!!!)
} ASErr  PlayNativeExport(SPBasicSuite *basic,char* newName)
     AIActionParamValueRef valueParameterBlock1 = NULL;
     AIActionManagerSuite *sAIActionManager;
    ASErr error =  basic->AcquireSuite(kAIActionManagerSuite,kAIActionManagerSuiteVersion,(const  void**)&sAIActionManager);
    if(error == kNoErr)
         ASErr result = sAIActionManager->AINewActionParamValue(&valueParameterBlock1);        
        if (valueParameterBlock1)
             result = sAIActionManager->AIActionSetString(valueParameterBlock1,kAIExportDocumentNameKey,newName );
             result = sAIActionManager->AIActionSetString(valueParameterBlock1,kAIExportDocumentFormatKey,  kAINativeFileFormat);
            result = sAIActionManager->AIActionSetString(valueParameterBlock1,kAIExportDocumentExtensionKey,kA INativeFileFormatExtension);
             result = sAIActionManager->AIActionSetBoolean(valueParameterBlock1,kAINativeCompressionKey,true);
             result = sAIActionManager->AIActionSetBoolean(valueParameterBlock1,kAINativePDFCompatibilityKey,tr ue);//when false, no preview at all
             result = sAIActionManager->AIActionSetInteger(valueParameterBlock1,kAINativeVersionKey,14);
             result = sAIActionManager->AIActionSetInteger(valueParameterBlock1,kAINativeScriptKey,1);
             result = sAIActionManager->AIActionSetInteger(valueParameterBlock1,kAINativeIncludeImagesKey,0);
             result = sAIActionManager->AIActionSetReal(valueParameterBlock1,kAINativeSubsetFontsRatioKey,100.0 );
             result = sAIActionManager->AIActionSetInteger(valueParameterBlock1,kAINativeEmbedProfileKey,0);
            if(result == 0)
                result =  sAIActionManager->PlayActionEvent(kAIExportDocumentAction,kDialogOff,valueParameterBlock1 );
             if(result != 0)
                error = result;
    basic->ReleaseSuite(kAIActionManagerSuite,kAIActionManagerSuiteVersion);
     return error;

Answer 1

Okay... Couldn't find anything in the documentation that updates the layer list other than the notifier that AP suggested.  A simple "sNotifier->Notify(kAILayerSetNotifier, message);" didn't seem to do the trick either.
Upon some simplified testing... Just deleting the layer and nothing else actually does delete the layer.  BUT.... deleting a layer and then immediately exporting an ai version of the file causes strange behavior.  As I said before, you get an exported file with a preview image that shows all the original layers, but the file does not actually contain the deleted layer.  AND when control is turned back to illustrator, all the original layers are still there.  It's as if illustrator deletes the layer from the document but not the list, then does the export which interupts the deletion, then when it gets control back it updates the document based on the list of layers and so it returns to it's previous state.  So weird.
You think there's a way to make it finish the deletion job before moving on to the export?