changeScene method error

When I call the changeScene method in the director class, I am receiving an error:

function nextScreen(event)

        if(event.phase == “ended”) then

            director:changeScene(“scripts.tags”);

        end

    end

yields:

Director ERROR: Failed to execute new( params ) function on ‘scripts.tags’

Not sure why this is. When I call the changeScene method elsewhere in my program it works. Any suggestions?