丢失参数字段当前值。 
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: CrystalDecisions.CrystalReports.Engine.ParameterFieldCurrentValueException: 丢失参数字段当前值。源错误: 
行 235: //产生报表Stream
行 236: Stream myReportStream;
行 237: myReportStream = myReport.FormatEngine.ExportToStream(myExpReq);
行 238: Response.ClearHeaders();
行 239: Response.ClearContent();
 源文件: f:\网站\stuarceducom\module\record\stuexaminfov.aspx.cs    行: 237 堆栈跟踪: 
[ParameterFieldCurrentValueException: 丢失参数字段当前值。]
   .I(String , EngineExceptionErrorID ) +574
   CrystalDecisions.CrystalReports.Engine.FormatEngine.internalSetReportInfo(RequestContext reqContext) +1293
   CrystalDecisions.CrystalReports.Engine.FormatEngine.internalGetViewContext(ReportPageRequestContext reqContext, * viewContext) +217
   CrystalDecisions.CrystalReports.Engine.FormatEngine.ExportToStream(ExportRequestContext reqContext) +184
   StuArcEduCom.Module.Record.StuExamInfoV.Page_Load(Object sender, EventArgs e) in f:\网站\stuarceducom\module\record\stuexaminfov.aspx.cs:237
   System.Web.UI.Control.OnLoad(EventArgs e) +67
   System.Web.UI.Control.LoadRecursive() +35
   System.Web.UI.Page.ProcessRequestMain() +731