Nonstop Backup like dead

My Nonstop Backup was functionning yesterday but it's gone from the list this morning (I never shut down this computer and Windows Update says nothing was done in that night either). I made a "Browse for backup" and opened the related file, and the Backup appeared again, but it was inactive: I could only "Recover". I deleted it (I have a complete disk backup elsewhere) and tried to rebuild it: no way. When I click "Start now" the window disappear but that's it, no new item appears on the list and no files are created on the chosen disk.