Hi I think stacking looks like a great tool, however when I try to use it
all the options are greyed out.

I am working with a collection.
I go to library grid mode.
Then I select several similar images using control left click.
Then I go to photo -> stacking and none the options are available?

If I select all then only move up/down and remove.
Almost like a collection is the same as a stack?

Stacks only work within the same folder

Yes I see now.

Wow that seems crazy.
I organise my folder on shooting date then place.
I wanted to work on collections independently of the folder structure.

I want to stack similar images from different shooting times
(i.e. folders) and then choose the best image from the stack.

I hope Adobe change this in the next release. I can't see
any reason for not allowing stacking across folders. It seems
opposite to everything lightrooom is about? Oh well: sigh

ok say i stacked my photos like 10 in one stack when i preview it in the browser i click on the album ( the stack) i cant see any of my other photos just the top one, anyone one know why?

Use S to toggle the stacks open and closed.