[XeTeX] problems with external figures

[Mojca Miklavec]

Hello,

I'm trying to include an image, but the following fails for some reason:

{\XeTeXpicfile 'a.jpg'}
\bye

! Unable to load picture or PDF file 'a.jpg}'.

Any ideas? I'm using
    XeTeX 3.141592-0.996 (Web2C 7.5.6)

Thanks a lot,
    Mojca