During my migration from the old .Text platform to the new SubText one, the main aspect of the entire process was to import all my previous posts and feedbacks.
SubText is wonderful on this aspect: it expose a feature that permits you to directly import your .Text database to the new platform but... during my migration process the import failed! 
I was worried because the error that the migration procedure gaves me was totally obscure. I've contacted an italian friend for any ideas about the error (thanks Simone) and fortunately he said me that on the source package there's also the SQL script used on the migration procedure.
So, I've opened the SQL script with SQL Server Management Studio and I've checked my Subtext database and my .Text ones... by checking the script code and the database, the error cause was clear. 
On my .Text database I had some tables where I've done my customizations during the years, so the table's owner was something different that dbo. (instead of dbo.mytablename on my db I had myadminuser.tablename). The script searches for dbo.mytablename on the two databases and this was the cause of the fail.
After a manual modification of this script, I've launched it manually and (as you can see) now all is ok...
Remember this "problem" if you plan to import your contents from .Text.