The DashboardViewer.CustomParameters event is raised before the Dashboard Viewer sends a query to a database server and allows you to specify parameter settings (for instance, specify a parameter value).
When current connection parameters do not allow you to connect to a data store (for instance, the server name is specified incorrectly), the DashboardViewer.ConnectionError event is raised. Handle the ConnectionError event and override the default behavior in this case.
This event is raised if the dashboard is supplied with data using the SQL/OLAP/Excel data source and the current connection parameters do not allow you to connect to a data store.
This event is raised each time the custom SQL query, which is used to supply the dashboard with data, needs to be validated. This is true if the SQL Data Source is used as a dashboard data source and the custom SQL query is used to select data.