SQL Server Reporting Service database version error

I was learning SQL Server 2005 reporting service, when I got this error during database setup:
Couldn't generate the upgrade script. There is no upgrade script available for this database version.
It seems that the database server that host the report server database is not the same with the reporting services installation.
I checked my database is SQL Server 2005 SP2, but I don't know my Reporting Service version.
Then I searched through Microsoft MSDN and found this page which tells me various ways to check reporting service version.
By checking the log file as suggested, I found that my Reporting Services is SQL Server 2005 SP1.
So now I am going to upgrade my reporting service.