Olive Whistler, Forest Raven, Flame Robin at New England NP but no sccrubbirds

I’ve just returned from a three-day campout at New England National Park west of Armidale, NSW. In good numbers here were Olive Whistler, Flame Robin and Forest Raven, with other nice birds including Red-browed Treecreeper and Scarlet Robin. However, there was no indication of the presence of Rufous Scrubbird in the beech forests around Pt Lookout which I understood had previously been a good site for this species. The habitat here looks excellent for the species and is far more extensive than at other sites where the bird persists (for instance, Border Ranges and Gloucester Tops). I wonder if anyone has thoughts on this? More here: http://sunshinecoastbirds.blogspot.com.au/2015/09/new-england-national-park-flame-robin.html Greg Roberts http://sunshinecoastbirds.blogspot.com.au/