calling the Render method returns Error

I am going to print a SSRS report from web application Asp.net 2010. I get below error when going to render the report by the parameters that already I've set. "This report requires a default or user-defined value for the report parameter 'Month'. To run or subscribe to this report, you must provide a parameter value"

I see the 'Month' parameter has nothing as default value even after it's set by me. any one can help please.

Here is some part of my code:

    parameters(0) = New ParameterValue()
    parameters(0).Name = LTrim(RTrim("Year"))
    parameters(0).Value = LTrim(RTrim("2016"))
    parameters(1) = New ParameterValue()
    parameters(1).Name = LTrim(RTrim("Month"))
    parameters(1).Value = LTrim(RTrim("009/2016 (March-2016)"))
    parameters(2) = New ParameterValue()
    parameters(2).Name = LTrim(RTrim("ServiceGroup")) 
    parameters(2).Value = LTrim(RTrim("ALL"))

    execInfo = rs.LoadReport(reportPath, historyID)

    rs.SetExecutionParameters(parameters, "fr-ch")

    SessionId = rs.ExecutionHeaderValue.ExecutionID
    Console.WriteLine("SessionID: {0}", rs.ExecutionHeaderValue.ExecutionID)


    Try
        result = rs.Render(format, devInfo, extension, _
           encoding, mimeType, warnings, streamIDs)

        execInfo = rs.GetExecutionInfo()

        Console.WriteLine("Execution date and time: {0}",          execInfo.ExecutionDateTime)


    Catch ex As SoapException
        Console.WriteLine(ex.Detail.OuterXml)
    End Try