Web Service consuming in C# issue

Question

I have 2 codes of different programs:

SWPlanilla wsn = new SWPlanilla();
string json = wsn.Report(dateini, hourini, dateend, hourend,readerid,panelid,typeid);

and:

SWPlanilla swp = new SWPlanilla();
json = swp.Report(textDateIni.Text,
                  dateTimeIni.Text,
                  textDateEnd.Text, 
                  dateTimeEnd.Text,
                  string_readers_selecteds, 
                  ((PanelAPMTC)comboBoxPanel.SelectedItem).id.ToString(),
                  1 + ""); 

The problem comes here. When I use the WS for a large date range, the WS generates and string(json), this have 2 parts: "message" and "type".Type is mmm practly indicates if the WS consuming was correct. and message is an string.The problem is is is, as i have a large date range, the json returned is very large and for that the WS returned a json like this: "{"type":"E","Json exceeds..."}".

The first one doesn't habe any problem and return me the string json correctly, but the second one, at the moment when performs the function of the WS 'report', throws an SoapException caused by the large json... I ve reviewed again and again both codes and doesn't find the problem :(