“Reporting Services Catalog Database File Existence” error during installing SQL Server 2008 R2

Question:

The reason:
I installed SQL Server 2008 R2 CTP before, and selected all components (including AS, RS, etc.) when installing RS, a database named ReportServer would be created by default, but the Database file of ReportServer was not cleared when uninstalling, and the installation path I chose this time was the same AS last time. This caused me to install SQL Server 2008 R2’s detection fail again.
 
Solutions:
Removes undeleted data files from the installation path. In %Program Files%\Microsoft SQL Server\ MSSQL10_50.msSQLServer \MSSQL\DATA\