Can't access last backup upgrading form Mountain Lion to Mavericks

Hello everyone,

I have a MacBook Pro 13" 2,53 Ghz Intel Core 2 Duo 4GB (mid 2009).

It run Mountain Lion, and I decided to clean instal Mavericks. I did it successfully (I guess) but now my problem is that I cannot access the last backup I performed in Mountain Lion. Trying to access manually my backup files, I can only see empty aliases.

Here is what I did:

- (in Mountain Lion) I performed a Time Machine backup in my usual external backup hard drive;

- after completing the backup, I connected my bootable Mavericks pen drive and I rebooted my Mac holding down "Option" key;

- I initialized my disk through disk utility (choosing as format "Mac OS Extended (journaled)");

- back in the boot menu I choose "Install OS X" and installed Mavericks successfully.

Now I have everything up and running but I cannot access in any way the files I thought I had saved in the last backup. Accessing the folders manually, they all seems empty aliases.Trying to access my old backups from Time Machine I have blank (meaning all black) windows.

The size of my backup hd is right, it seems that everything should be there, but no way to access it.

Would it help to downgrade back to Mountain Lion?

Can please somebody help me with this? It's very important.

Thank you all in advance.