[luabind] pass by ref, no matching overload found

[Сергей В. <iva...@gm...>]

I want to pass parameters in method by reference.

class Node : public EventReceiver
{
public:
virtual void setTag ( const std::string& name, const std::string& value )
...
};

And this is luabind code to expose Node to lua:
class_<Node, EventReceiver> ( "Node" )
.def ( constructor<> () )
.def ( "setTag", &Node::setTag )
...

I want to set tag for node from lua script:
node = scene:find ( "NewGameButton" )
node:setTag ( "scale", value )

I get luabind error:
No matching overload found, candidates:
void setTag(Node&,std::string const&,std::string const&)

But this line works fine
node:setTag ( "scale", "str_value" )

How to get setTag working in both cases?