Hi, I get below error when I do following function call. Can anyone help me understanding the error.

get_entry_result_for_reports report_entries = this.sugarClient.get_report_entries(this.sessionId , new string[] { reportID }, null);

ERROR
System.InvalidOperationException was unhandled by user code
Message=There is an error in XML document (1, 532).
Source=System.Xml
StackTrace:
at System.Xml.Serialization.XmlSerializer.Deserialize (XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
at System.Xml.Serialization.XmlSerializer.Deserialize (XmlReader xmlReader, String encodingStyle)
at System.Web.Services.Protocols.SoapHttpClientProtoc ol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtoc ol.Invoke(String methodName, Object[] parameters)
at sugarsoap.get_report_entries(String session, String[] ids, String[] select_fields)
at SugarCRM.BusinessLayer.SugarHelper2.GetReportEntri es(String reportID) in C:\APAsite\SugarCRM\SugarCRM\BusinessLayer\SugarHe lper2.cs:line 203
at SugarCRM.Default2.Page_Load(Object sender, EventArgs e) in C:\APAsite\SugarCRM\SugarCRM\Default2.aspx.cs:line 43
at System.Web.Util.CalliHelper.EventArgFunctionCaller (IntPtr fp, Object o, Object t, EventArgs e)
at System.Web.Util.CalliEventHandlerDelegateProxy.Cal lback(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
InnerException: System.InvalidOperationException
Message=The specified type was not recognized: name='field_list', namespace='http://www.sugarcrm.com/sugarcrm', at <field_list xmlns=''>.
Source=System.Xml
StackTrace:
at System.Xml.Serialization.XmlSerializationReader.Ge tPrimitiveType(XmlQualifiedName typeName, Boolean throwOnUnknown)
at System.Xml.Serialization.XmlSerializationReader.Re adArray(String typeName, String typeNs)
at System.Xml.Serialization.XmlSerializationReader.Re adReferencingElement(String name, String ns, Boolean elementCanBeType, String& fixupReference)
at System.Xml.Serialization.XmlSerializationReader.Re adReferencingElement(String name, String ns, String& fixupReference)
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlS erializationReadersugarsoap.Read8_get_entry_result _for_reports()
at System.Xml.Serialization.XmlSerializationReader.Re adReferencingElement(String name, String ns, Boolean elementCanBeType, String& fixupReference)
at System.Xml.Serialization.XmlSerializationReader.Re adReferencingElement(String name, String ns, String& fixupReference)
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlS erializationReadersugarsoap.Read29_get_report_entr iesResponse()
at Microsoft.Xml.Serialization.GeneratedAssembly.Arra yOfObjectSerializer13.Deserialize(XmlSerialization Reader reader)
at System.Xml.Serialization.XmlSerializer.Deserialize (XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
InnerException: