I would persist, as hard as it sounds, in a few months you will look back on this and think, I'm glad I did hang it out - because in my experience the vast majority of children do eventually 'get there'.

I remember one little boy who used to curl up in one spot and cry all day, then it progessed to eating on that spot, then sitting up paying attention to what was going on around him in that spot. After a number of weeks, (with mum and staff working together closely), he eventually decided it would seem that joining in the fun out weighed the sadness. Now if you look at that little boy, you would never know what he was like to begin with.