[XeTeX] Problem with XeTeX letterspacing

[Stephen Moye]

I am having a problem with the neat letterspacing function of XeTeX.  
If I indicate that I want letterspacing using a given font, then the  
next font is reduced in size:

\font\rm="Doves-roman" at 22pt \rm
%% Here is the problem: use the letterspaced  caps font and the title
%% font text is tiny; use the caps font without the letterspacing, and
%% text using the \title font appears at the correct size.
\font\caps="Doves-roman:letterspace=5.0" at 22pt
%\font\caps="Doves-roman" at 22pt\rm
\font\title="DovesTitle" at 63pt

I have placed sample files in an archive for downloading:

http://homepage.mac.com/stephenmoye/FileSharing7.html

A puzzle.

Thanks for any help.