Today I have noticed that SCOM reports that are scheduled to be delivered as e-mail attachments do not contain chart data.
At the time when affected scheduled report is executed, the following event is logged in Application log of the server running SQL Reporting Services:
Log Name: Application
Source: Report Server Windows Service (MSSQLSERVER)
Event ID: 108
Report Server Windows Service (MSSQLSERVER) cannot load the EnterpriseManagementChartControl extension.
After some investigation, it turned out that this is a know issue which is documented in the following knowledge base article:
Scheduled reports that you create by using SQL Server 2008 Reporting Services (SSRS) do not display chart data in System Center Operations Manager 2007 R2 – http://support.microsoft.com/kb/972821
After editing ReportingServicesService.exe.config file, you should be able to see chart inlcuded in SCOM report.