TypeError when using AssetLibrary.fromManifest

I am building an AssetLibrary using this code:

var manifest = new AssetManifest();
for(theAsset in assetsList){

		case AssetType.IMAGE:
			manifest.addBitmapData ("assets/" + theAsset.att.src);
		case AssetType.TEXT:
			manifest.addText("assets/" + theAsset.att.src);
		case AssetType.BINARY:
			manifest.addBytes("assets/" + theAsset.att.src);
			manifest.addBytes("assets/" + theAsset.att.src);



AssetLibrary.loadFromManifest (manifest).onComplete (function (library:AssetLibrary) {

		Assets.registerLibrary (libName, library);

	}).onError (function (e) {

	trace (e);

This compiles to HTML5 fine, but Flash gives this error:

TypeError: Error #1034: Type Coercion failed: cannot convert lime.utils::[email protected] to openfl.utils.AssetLibrary.
at MethodInfo-3709()
at MethodInfo-1144()
at lime.app::Promise_lime_utils_AssetLibrary/complete()
at lime.utils::AssetLibrary/__assetLoaded()
at lime.utils::AssetLibrary/loadImage_onComplete()
at MethodInfo-3124()
at lime.app::Promise_lime_graphics_Image/complete()
at MethodInfo-1926()

Any ideas?

My relevant imports are:

	import openfl.utils.Assets;
	import openfl.utils.AssetLibrary;
	import openfl.utils.AssetManifest;
	import openfl.utils.AssetType;

I have other hiccups now but I believe that adding this line has solved that particular Type Coercion problem:

manifest.libraryType = "openfl.utils.AssetLibrary";