[XeTeX] No ligatures, dashes and typographical quotes after changing font

[Alexander Schultheiß]

After changing my main font in XeTeX I've lost all niceties of TeX,
like ligatures (fi, ffi), em/en dashes, typographical quotes &c. The
font decalrations are as follows:

--------------------------------------------------------------------------------
\font\eighteenrm="[/path/to/fonts/myfontrm.ttf]:script=latn" at 18truept
\font\eighteensl="[/path/to/fonts/myfontsl.ttf]:script=latn" at 18truept
\font\eighteenit="[/path/to/fonts/myfontit.ttf]:script=latn" at 18truept
\font\eighteenbf="[/path/to/fonts/myfontbf.ttf]:script=latn" at 18truept
\font\eighteenbi="[/path/to/fonts/myfontbi.ttf]:script=latn" at 18truept
\font\eighteensc="[/path/to/fonts/myfontsc.ttf]:script=latn" at 18truept

\font\forteenrm="[/path/to/fonts/myfontrm.ttf]:script=latn" at 14truept
\font\forteensl="[/path/to/fonts/myfontsl.ttf]:script=latn" at 14truept
\font\forteenit="[/path/to/fonts/myfontit.ttf]:script=latn" at 14truept
\font\forteenbf="[/path/to/fonts/myfontbf.ttf]:script=latn" at 14truept
\font\forteenbi="[/path/to/fonts/myfontbi.ttf]:script=latn" at 14truept
\font\forteensc="[/path/to/fonts/myfontsc.ttf]:script=latn" at 14truept

\font\thirteenrm="[/path/to/fonts/myfontrm.ttf]:script=latn" at 13truept
\font\thirteensl="[/path/to/fonts/myfontsl.ttf]:script=latn" at 13truept
\font\thirteenit="[/path/to/fonts/myfontit.ttf]:script=latn" at 13truept
\font\thirteenbf="[/path/to/fonts/myfontbf.ttf]:script=latn" at 13truept
\font\thirteenbi="[/path/to/fonts/myfontbi.ttf]:script=latn" at 13truept
\font\thirteensc="[/path/to/fonts/myfontsc.ttf]:script=latn" at 13truept

\font\twelverm="[/path/to/fonts/myfontrm.ttf]:script=latn" at 12truept
\font\twelvesl="[/path/to/fonts/myfontsl.ttf]:script=latn" at 12truept
\font\twelveit="[/path/to/fonts/myfontit.ttf]:script=latn" at 12truept
\font\twelvebf="[/path/to/fonts/myfontbf.ttf]:script=latn" at 12truept
\font\twelvebi="[/path/to/fonts/myfontbi.ttf]:script=latn" at 12truept
\font\twelvesc="[/path/to/fonts/myfontsc.ttf]:script=latn" at 12truept

\font\tenrm="[/path/to/fonts/myfontrm.ttf]:script=latn" at 10truept
\font\tensl="[/path/to/fonts/myfontsl.ttf]:script=latn" at 10truept
\font\tenit="[/path/to/fonts/myfontit.ttf]:script=latn" at 10truept
\font\tenbf="[/path/to/fonts/myfontbf.ttf]:script=latn" at 10truept
\font\tenbi="[/path/to/fonts/myfontbi.ttf]:script=latn" at 10truept
\font\tensc="[/path/to/fonts/myfontsc.ttf]:script=latn" at 10truept
--------------------------------------------------------------------------------

TeXDistro:     TeXLive 2009 (XeTeX)
OS:	       Slackware 12.2

What do I miss?

Thanks,
Alex

P.S. The font has ligatures as well as all dashes and quotes at their
respective unicode codepoints; at liest the rm version.