Null 2008 SSRS Parameters

Question

How do you pass parameters nullto a SQL 2008 report? The code that interacts with the ReportExecution and ReportService2005 web services always throws an error when executing the method ReportExecutionService.Render()after I set the parameters (not including null) by calling the method ReportExecutionService.SetExecutionParameters():

"...This report requires a default or user-defined value for the report parameter...to run or subscribe to this report, you must provide a parameter value."

although this option is defined in the .rdl file as capable nullby default null.

Should I change my code? Change settings in a .rdl file?

var rs = new ReportExecutionService();
rs.Url= "http://Z/ReportServer/ReportExecution2005.asmx";     
rs.Credentials = CredentialCache.DefaultCredentials;
rs.ExecutionHeaderValue = new ExecutionHeader();

var executionInfo = rs.LoadReport(ReportTarget, null);
var parameterList = new List<ParameterValue>();

foreach (ParameterValue parameter in Parameters)
{
  parameterList.Add(parameter);
}

foreach (var expectedParameter in executionInfo.Parameters)
{
  if 
  (  
      expectedParameter.Nullable && 
      !parameterList.Exists(delegate(ParameterValue pv) 
      { return pv.Name == expectedParameter.Name; })
  )
  {
     var parameter = new ParameterValue();
     parameter.Name = expectedParameter.Name;
     parameter.Value = null;

     parameterList.Add(parameter);
  }
}

rs.SetExecutionParameters(parameterList.ToArray(), "en-us");

Warning[] warnings = null;
string[] streamIDs = null;
string encoding = null;
string extension = null;
string mime = null;

var content = rs.Render("PDF", null, out extension, out mime, out encoding, out warnings, out streamIDs);

Answer 1

SSRS. , , null , "... ..."

, VB.

params = New ArrayList

...

Dim ssrsPrm As New Microsoft.Reporting.WebForms.ReportParameter(param.Name)
ssrsPrm.Values.Add(Nothing)
params.Add(ssrsPrm)

...

Me.ReportViewer1.ServerReport.SetParameters(DirectCast(params.ToArray(GetType(Microsoft.Reporting.WebForms.ReportParameter)), Microsoft.Reporting.WebForms.ReportParameter()))

Answer 2

? , , .