HtmlImporter is not working

My version of TLF is 502 (715519).

When i try to use HtmlImporter with folowing code:

var importer:HtmlImporter = new HtmlImporter(this._mainTextFlow.configuration);

var textFlow:TextFlow = importer.importToFlow(XML('<font color="#FF0000">hello world</font>'));

it's throw an errors:

1046: Type was not found or was not a compile-time constant: HtmlImporter.

1180: Call to a possibly undefined method HtmlImporter.

Using TextLayoutImporter, for example, doesn't throws similar errors.

Any ideas?

UPD: omg, using TextLayoutExporter throws similar errors. I'm scared.

Sorry for bad eng