HELP - split by scenes problem

[henk]

I use Windows XP with MSI motherboard, with onboard firewire,
MSP 6.5 and a Panasonic DVcamcorder with timecode.
I capture from DV ( with Ulead Directshow, camcorder is detected fine ) to .avi.
Inserted in the editor I want the large avi to split by scene,
however there is always only one scene detected (open by scene is ticked). I tried different files, no result.

I used this in the past (older PC, older camcorder, same MSP) and then
it worked fine.

What can be wrong?