Clip monitor not working?

Hi,

i want to contribute to this great programm (and also freshen up my C++-skills working on some real project ;-) ). To get started i compiled everything from sources (thanks to the buildscript posted somewhere on this forum!). Before really diving into the code i want to make sure my environment is fine. One thing i noticed immediately: The clip monitor does not show any image when playing back. Also no sound is produced. But the project monitor is working fine - when i add the clip to the timeline it is shown correctly, also with effects, transitions etc.
Is this a known issue of current svn or something broken on my side?

Thanks
Michael