how can I reorder a dendrogram?

Hi!

I am trying to reorder a dendrogram via reorder.dendrogram. However, I 
observed some problems with this, and I will illustrate them with an 
example.

Take the following clustering problem:

datamatrix <- matrix(c(2,2,2.5,2,1.5,2,2,1.5,2,2.5, 
6,2,6.5,2,5.5,2,6,1.5,6,2.5, 4,4,4.5,4,3.5,4,4,3.5,4,4.5), ncol=2, 
byrow=TRUE)
distmatrix <- dist(datamatrix, method="manhattan")
hc <- hclust(distmatrix, method="single")
dendro <- as.dendrogram(hc)

The datamatrix contains three equidistant (for manhattan distance) 
clusters, each of which contains 5 points.
Now, I want to impose an order:

weights <- c(2.0, 2.0, 2.0, 2.0, 2.0, 6.0, 6.0, 6.0, 6.0, 6.0, 4.0, 4.0, 
4.0, 4.0, 4.0)
ddd <- reorder(dendro, weights, agglo.FUN=mean)

but if you compare the order of ddd with dendro, you see no change:

unlist(ddd)
[1] 15 14 13 11 12  5  4  3  1  2 10  9  8  6  7

unlist(dendro)
[1] 15 14 13 11 12  5  4  3  1  2 10  9  8  6  7

I would have expected something like:
5  4  3  1  2 15 14 13 11 12 10  9  8  6  7

or something of the sort. (I still do not know, if the order should be 
ascending or descending, but in the obtained result, it is neither nor). 
I do not see, where my mistake is ...

Thanks for your advice!

Thomas.