setting letter paper size

[Kieren Richard MacMillan]

[ Mac OS X 10.2.8 (Fink);  Lilypond 2.1.17-1 ]

Hello, all --

I can't seem to change the paper size correctly after converting my 
files to 2.1.17-1...

I tried

    #(set-paper-size "letter")

and

    hsize = 8.5 \in
    vsize = 11.0 \in

in the \paper block, but I ended up with an a4 (ca 8.2 x 11.6 in) page 
in both cases.

Any help would be appreciated!

Best wishes,
Kieren.