Windows Back-Up(centre) stopped automatic BU

Since 2 weeks it has stopped.
In the BU-centre Wizard at "What drives you want in the back-up
record?" is written:

Stations
Unknown (C (Missing) - 0 bytes - 0 bytes
Unknown (E (Missing) - 0 bytes - 0 bytes
They are unchecked and greyed-out (uncheck able)

The C: is on a SSD on SATA 1 and the E: drive is on an old-fashioned
drive on SATA 3.
On SATA 2 a disk entirely is taken by Linux (Ubuntu).

The start-up sequence in the BIOS is SATA2 (Linux), 1 (Windows Vista
Buss.), 3 (Windows data)
At start-up first a boot manager asks if I will start Ubuntu or
Windows: then, choosing Windows, Vista starts (the Windows Boot
Manager exists, but has only one choice (Windows) and therefore does
not appear).

Does it has to do with the boot sequence?
Who knows the answer(s)?
(In the Dutch MS.Vista Newsgroup I got 0 answers.)