Error on upgrade 2.5 to 2.6

Hi

Just upgraded from 2.5 to 2.6 & ran into a problem

I am not seeing my site, just getting the error page.

I think I have done everything correctly, ran upgrade.sql, deleted 2.5, uploaded 2.6, replaced /App_Data/InstalledPlugins.txt
& /App_Data/Settings.txt plus my custom files.

I found an error when I ran  the sql script - not sure if this is the source of the problem or not.

Error  1  Cannot find either column "nref" or the user-defined function or aggregate "nref.value", or the name is ambiguous.  upgrade.sql  870  8  Miscellaneous Files
Error  2  Cannot find either column "nref" or the user-defined function or aggregate "nref.value", or the name is ambiguous.  upgrade.sql  870  46  Miscellaneous Files
Error  3  Cannot find either column "dbo" or the user-defined function or aggregate "dbo.nop_getprimarykey_indexname", or the name is ambiguous.  upgrade.sql  2608  18  Miscellaneous Files
Error  4  Cannot find either column "dbo" or the user-defined function or aggregate "dbo.nop_getprimarykey_indexname", or the name is ambiguous.  upgrade.sql  2614  18  Miscellaneous Files
Error  5  Cannot find either column "dbo" or the user-defined function or aggregate "dbo.nop_getprimarykey_indexname", or the name is ambiguous.  upgrade.sql  2620  18  Miscellaneous Files
Error  6  Cannot find either column "nref" or the user-defined function or aggregate "nref.value", or the name is ambiguous.  upgrade.sql  2689  23  Miscellaneous Files
Error  7  Cannot find either column "nref" or the user-defined function or aggregate "nref.value", or the name is ambiguous.  upgrade.sql  2689  61  Miscellaneous Files
Error  8  Invalid column name 'AllowGuestsToVote'.  upgrade.sql  2783  5  Miscellaneous Files
Error  9  Invalid column name 'AllowGuestsToVote'.  upgrade.sql  2784  7  Miscellaneous Files

Any help gratefully received.

Ok, gone through the whole procedure again, third times a charm!

Now have a working site, though appear to now have problems applying my theme from 2.5.

I see from other posts i need to use a file comparison to manually apply changes to the views I've altered.
Is this the only way of updating a theme?

Sorry for "newbie" questions, first time upgrading  nopcommerce & learning as I go.

I must say on the whole I like the cart, nice to see a good .net solution!

I experience the same problem with the errors upon executing the upgrade script.