Odd behavior with distribute centers

Question

My problem is that the distribute commands are working but ignoring the order of my layers.
Say for example I have an item in the bottom left of the page, and another in the top right of the page.  I have several other items on their own layers between the other two.  If I select all of those layers and link them, then use the distribute centers options, the horizontal distribution works as expected with the items starting to the left and then moving gradually to the right in ascending layer order.
However if I use distribute vertical centers, the items will ignore the order of the layers and distribute them in opposite order.  It even takes the bottom layer (bottom left item) and moves it second furthest to the right.  The result is that I end up with a distribution that starts on the right, and moves up and to the left, then takes the top layer and leaves it where it was before.
What am I doing wrong that causes the distribution process to ignore the relative order of the layers?
Another note is that I am at work, and only have Photoshop CS2 Available.  I do not have photoshop at home and will not be able to test any additional theories until Monday but I will try and follow up.
-Brandon

Answer 1

Photoshop senses that the objects in the first set of 5 actually go downhill slightly, so Photoshop tries to keep that "downhill" arrangement.  Even if they're just one pixel off from perfect alignment, it tries to keep the highest one highest, the second highest one second highest and so on.
If the objects are all EXACTLY on the same coordinate, then it distributes them by layer order, moving the lowest layer first.
So the proper way to use the tool is to get the objects close by hand, then use the alignment features to fine tune their positions.
Examples:
Note that the A through E bubbles go just slightly downhill here.
Here the layers are in the same order as above, but the A through E bubbles go slightly uphill.
In this case, A through E are all exactly on the same pixel vertically, and the layers are ordered A through E, bottom to top:
Here, A through E are aligned exactly vertically again, but their layer order has been reversed:
Hope this helps clarify things.
-Noel