EXTJS + drag and drop

Hello friends
I need to configure the extjs drag and drop but somehow i am not able to display it.

my controller contains the following code

def index
respond_to do |format|
format.html
format.ext_json { render :json => User.all.to_ext_json }
end
end

and in the index.erb

I have included all the necessary js file which is required by extjs

But no idea why the things are not coming up.

NOTE: the extjs drag & drop window is coming up but no data inside.

Thanks
abhis