I want to show my report in a ReportViewer control, but when I click on the arrow in the Report property from the property grid, it does not show available reports - what is wrong?

Make sure that to follow our best practices and have the report in a separate code library that is referenced in the web app/site. Check if the class library containing the report is referenced in your app/site and that you have rebuilt your app/site.

The most reliable way to specify a report for the ReportViewer is to do this programmatically. For example if you're using the ASP.NET report viewer, on Page_Load event of the page:

Example

CopyC#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        var instanceReportSource = new Telerik.Reporting.InstanceReportSource();
        instanceReportSource.ReportDocument = new Telerik.Reporting.Examples.CSharp.ListBoundReport();
        this.ReportViewer1.ReportSource = instanceReportSource;
    }
}

CopyVB.NET

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim instanceReportSource As New Telerik.Reporting.InstanceReportSource()
        instanceReportSource.ReportDocument = New ListBoundReport()
        ReportViewer1.ReportSource = instanceReportSource
        ReportViewer1.RefreshReport()
    End If
End Sub

A multi-column report shows fine when using Preview, but when used as a subreport, it shows as a one-column report only

The multi-column functionality is intended to be used only in the main report because all report sections (excluding Page sections) are rendered in a column-wise layout, thus the report can be wide only one column.