Team Foundation Server Installation Problem

While setting up Team Foundation Server 2008 in a dual-server configuration, the installation stopped towards the end with the error message:

Error 28805: The setup program cannot complete the request to the server that is running SQL Server Reporting Services. Verify that SQL Server Reporting Services is installed and running on the Team Foundation app tier and that you have sufficient permissions to access it. For more information, see the setup log.

The actual error recorded in the setup log was:

Cannot finish the request on Microsoft SQL Server Reporting Server. Please check that Microsoft SQL Server Reporting Services and Windows service are running and you have sufficient privileges on the data tier:
System.Web.Services.Protocols.SoapException: The report server installation is not initialized. (rsReportServerNotActivated) —> The report server installation is not initialized. (rsReportServerNotActivated)
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object parameters)
at Microsoft.TeamFoundation.Proxy.Reporting.ReportingService.CreateDataSource(String DataSource, String Parent, Boolean Overwrite, DataSourceDefinition Definition, Property Properties)
at Microsoft.TeamFoundation.Client.Tools.createds.Program.Run(String args)

Data source creation failed.

So, according to the installation instructions, the TFS installation is supposed to initialize (and I assume activate) the report server.

So what was the problem? It turns out that to fix it, I had to go into Report Services Configuration Manager, and on the Encryption Keys tab, I had to select Delete. After that, the installation continued on with no problem. Go figure.