Icecast - Nov 2009 - fallback file for FLAC stream

Hello,

I'm running FLAC streaming on Icecast-2.3.2 server and it works great for 
long time.
Now I tried to define fallback-mountpoint for it.
This fallback mount would be a file located in Icecast webroot. But 
Icecast doesn't accept any FLAC file I created. It writes warning:

"WARN source/source_move_clients stream /test-fallback.flac and /test.flac
are of different types, ignored"

I tried to create test-fallback.flac file with Ogg as transport layer,
I tried to capture live FLAC stream into file and then use it as 
test-fallback.flac, no success.

I'm using following definition:

     <mount>
         <mount-name>/test.flac</mount-name>
         <fallback-mount>/test-fallback.flac</fallback-mount>
         <fallback-override>1</fallback-override>
     </mount>

Other fallback-mountpoints for mp3 streams work nice for me.

So - is here any way how could I create correct file for using it as 
fallback file for FLAC stream?
Or could you recommend me how to do fallback for FLAC stream?

Thank you for help,

  Milos