Some of my computers does not download files from ubuntu one

Hello!

I've got some computers, in different towns; Ubuntu one makes my life easier, letting me sync files without bringing disks or pendrives.

But...

I noticed that some files are ignored, not downloaded, into one machine, and some aren't uploaded from other machines.

I suppose that he local index "knows" the files being on the server, and "feels" that they have been downloaded.
Is there a way to make the client verify the actual content of the folders with he cloud?

 I have tried removing ~/.config/ubuntuone, without any result.

Thnks for reading,
Riccardo