C# Error: Value cannot be null, Parameter name: type

[Konstantinos]

In a very few specific places in the product my company has built, we are using Telerik Reports in C#.

Report is trying to reach a stored procedure with 2 params: @languageCode and @invoicePaymentReceiptID

Creating a PDF Report however is giving me the below error:

ERROR

Value cannot be null.
Parameter name: type

STACK TRACE

   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.Activator.CreateInstance(Type type)
   at Telerik.Reporting.Processing.TypeReportDocumentResolver.Resolve(IProcessingContext context, TypeReportSource rs)

DLL VERSION

Telerik.Reporting, Version=9.1.15.731, Culture=neutral, PublicKeyToken=a9d7983dfcc261be

CODE

 Telerik.Reporting.Processing.ReportProcessor reportProcessor = new Telerik.Reporting.Processing.ReportProcessor();
 System.Collections.Hashtable deviceInfo = new System.Collections.Hashtable();
 Telerik.Reporting.TypeReportSource typeReportSource = new Telerik.Reporting.TypeReportSource();
 typeReportSource.TypeName = frmR.reportName;
 typeReportSource.Parameters.Add(new Telerik.Reporting.Parameter("languageCode", frmMain.language));
 typeReportSource.Parameters.Add(new Telerik.Reporting.Parameter("invoicePaymentReceiptID", 20421));
 //typeReportSource.Parameters.Add(new Telerik.Reporting.Parameter("reportID", tsbReportList.ComboBox.SelectedValue));
 Telerik.Reporting.Processing.RenderingResult result = reportProcessor.RenderReport("PDF", typeReportSource, deviceInfo);

 

It hits in the last line, trying to create the PDF report. 
Any ideas on the topic would be much appreciated.

Thank you.