Well thank for your reply.
1) well I thought it was possible to install it on the N900 internal memory thats why...

2)yes am in windows but i have Ubuntu on dualboot too (if this may help)

yes I have enabled storage mode, I use to get N900 as name of the mass storage but here I have just disc amovible.

between, I installed Storage Usage And it only show my RootFS. Flashed it two times but nothing.