getDefinitionByName does not work in worker

Question

public static function registerClassAliasByClassName(className:String):void
    {
        var ClassReference:Class = getDefinitionByName(className) as Class;
        var commandAliasRegister:CommandAliasRegister = new ClassReference();
        commandAliasRegister.register();
    }

getDefinitionByName work in main Worker, but does not work in secondary thread. I have this error:

ReferenceError: Error #1065: Variable LoaderCommandAliasRegister is not defined.
at global/flash.utils::getDefinitionByName()

I have this error because off in secondary thread other ApplicationDomain. Exists path fix this problem?

Sorry for my English.