Parameters in Reporting Services - C# Syntax

I'm using code from microsoft's website and I'm getting the following error:
"The type or namespace name 'ParameterValue' could not be found (are you missing a using directive or an assembly reference?)"
What am I doing wrong here? I want to pass parameters to the .render method.
// Prepare report parameter.
ParameterValue[] parameters = new ParameterValue[3]; <-- error occurs on this line
parameters[0] = new ParameterValue();
parameters[0].Name = "EmpID";
parameters[0].Value = "38";
parameters[1] = new ParameterValue();
parameters[1].Name = "ReportMonth";
parameters[1].Value = "6"; // June
parameters[2] = new ParameterValue();
parameters[2].Name = "ReportYear";
parameters[2].Value = "2004";
i figured it out
i had to add ReportServer before ParameterValue
i.e. ReportServer.ParameterValue[] parameters = new ReportServer.ParameterValue[3];