No fallback to slave server

[Ge2rt]

I've defined two servers:

1. master server / normal server / no SSL / retention 14 days (active)
2. slave server / fill server / no SSL / retention 500 days (active)

When 'feeding' Newsbin with a nzb containing files older than 14 days, files are not downloaded from the slave server. Fallback is not working.
It's working fine when installing V5 again.

OS: Windows Vista Ultimate x64
Newsbin: V6.0b8 - V6.0b11 (build 918)