Font Weight, can't use a light font

Migrateduser

<p><span>Hey everybody,<br><br>
I want to use a light font in my report.<br><br>
For standard text i have a style with the font but if i change the weight (see screenshot), nothing happens. Only bold and bolder works, but not lighter.<br>
The light font is installed and recognised by other applications.<br>
I tried multiple fonts with the same result.<br><br>
I work on Mac OS X and usually with Birt 4.3.2 but also tested on 4.6.<br><br>
I created a hacky workaround with changing the light font into a own new font family, but the server which should later generate the pdfs do not recognize it.</span></p>