Stimual soft report - stimulsoft

Question

on sending the data to the report this error is shown to me
the businesses object is 5 column of strings named ReportData
public ActionResult GetReport()
{
List ItemExpiredReportViewModelList = new List();
for (int i = 0; i < 10; i++)
{
ItemExpiredReportViewModel ItemExpiredReportViewModela = new ItemExpiredReportViewModel();
ItemExpiredReportViewModela.ItemName = "ItemName ".ToString();
ItemExpiredReportViewModela.ItemCode = "ItemCode ".ToString();
ItemExpiredReportViewModela.ItemUnit = "ItemUnit ".ToString();
ItemExpiredReportViewModela.ExpireDate = "ExpireDate".ToString();
ItemExpiredReportViewModela.Balance = "Balance ".ToString();
ItemExpiredReportViewModelList.Add(ItemExpiredReportViewModela);
}
StiReport report = new StiReport();
report.Load(Server.MapPath("~/Areas/Admin/Reports/TestStimulsoft/Report.mrt"));
report.RegBusinessObject("ReportData", ItemExpiredReportViewModelList);
report.Compile();
CheckReference(report);
return StiMvcViewer.GetReportResult(report);
}
c:\Users\user\AppData\Local\Temp\s3iq5rsq.0.cs(950,13) : error CS0126: An object of a type convertible to 'string' is requiredc:\Users\user\AppData\Local\Temp\s3iq5rsq.0.cs(955,13) : error CS0126: An object of a type convertible to 'string' is requiredc:\Users\user\AppData\Local\Temp\s3iq5rsq.0.cs(960,13) : error CS0126: An object of a type convertible to 'string' is requiredc:\Users\user\AppData\Local\Temp\s3iq5rsq.0.cs(965,13) : error CS0126: An object of a type convertible to 'string' is requiredc:\Users\user\AppData\Local\Temp\s3iq5rsq.0.cs(970,13) : error CS0126: An object of a type convertible to 'string' is required
at Stimulsoft.Report.StiReport.Compile(String path, Stream stream, StiOutputType outputType, Boolean autoCreate, Object standaloneReportType) in D:\Stimulsoft\Stimulsoft.Reports\Stimulsoft.Report\StiReport.Compile.cs:line 435
at Stimulsoft.Report.StiReport.Compile() in D:\Stimulsoft\Stimulsoft.Reports\Stimulsoft.Report\StiReport.Compile.cs:line 134
at HMS.Web.Areas.Admin.Controllers.AddTransactionController.GetReport() in D:\HMS3\HMS.Web\Areas\Admin\Controllers\AddTransactionController.cs:line 405
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c.b__9_0(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult2.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase1.End()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.b__11_0()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass11_1.b__2()