[ruby-talk:04234] @ variables not updated within method?

I have a program, too large to post here, and an object in it with a
variable:

@chunks = Hash.new([])

in my initialize() method

It is a hash of arrays.  I am finding that it is not updated when 
it should be.  @chunks.inspect always seems to give me 

{}

even though I do update various elements.  At the same time, as I access
the keys I can get at the contents of the arrays, but sometimes the wrong
keys are updated.  I am only filling the hash with strings and numbers, so
they should be easily displayed with inspect.

Are there any catches I should be looking out for when doing this sort of 
thing?

	Hugh
	[e-mail]