How can I debug fragment cache or expire all ?

I have been using fragment caching and it seemed like it was working
pretty well.
I added some things and now it is not working.

Could I have screwed it up if I deleted the cache files by hand that
it had in the temp directory ? Even if I did that, when I re execute
the statement: expire_fragment(%r{ticket/get_page.*}) . I would think
I would be back in business.

I all the the cache this:
cache(:action => 'get_page', :page => @page, :order => @order, :fields
=> @fields.join(','), :conditions => @tk_conditions) do

and nothing happens, it no longer creates a file.

My read is like this, but it no longer gets anything as the cache()
method doesn't create anything.
@fragment = read_fragment({:action => 'get_page', :page => @page,
                                        :order => @order, :fields =>
                                        :conditions => @tk_conditions})

First do these two tasks and see if it works

1) check whether your cache directory has read and write permission, &
2) run 'rake tmp:clear' from your app root and restart your server

I hope this should solve your problem.