not able to upload file from jqgrid

not able to upload file from jqgrid

I am trying to upload a text file from JQgrid edittype file option. But when clicking on submit button on add dialoge its not calling web method. Please help.

Below is my grid col model:
jQuery( "#JQGridFileUpload" ).jqGrid({ 

                colNames: [ 'ClientID' , 'Document Type' , 'Document Description' , 'View/Upload documents' ],

                colModel: [


                        {

                            name: 'DocumentType' , index: 'DocumentType' , width: 30, editable: true ,

                             edittype: 'select' , editoptions: { value: ClientDocumentType }

                        },

                         {

                             name: 'DocumentName' , index: 'DocumentName' , width: 30, editable: true ,

                             edittype: 'file' , editoptions: {

                                 enctype: "multipart/form-data"

                             },                           

                             formatter: 'showlink' ,

                             formatoptions: { baseLinkUrl: 'javascript:' , showAction: "ShowFile('" , addParam: "');" }

                         }

                ],

                            });



$( '#JQGridFileUpload' ).jqGrid( 'navGrid' , '#JQGridFileUploadPager' ,

                                           {

                                               edit: true ,

                                               add: true ,

                                               del: true ,

                                               search: false ,

                                               refresh: true

                                           },                                          

                                            //Edit functionality

                                             {  

                                             },

                                             //Add functionality

                                             {

                                                                                                                                         url: 'ClientMaster.aspx/InsertDocumentDetails' ,

                                                  closeAfterAdd: true ,

                                                 reloadAfterSubmit: false ,

                                                 closeAfterAdd: true ,

                                                  afterSubmit: function (options, postData, response) {

                                                 var filename = $( "#DocumentName" ).val();

                                                     var files = $( "#DocumentName" ).val();

                                                                                                          $.fn.ajaxFileUpload

                                                         (

                                                             {

                                                                url: 'ClientMaster.aspx/InsertDocumentDetails' ,

                                                                 secureuri: false ,

                                                                 fileElementId: 'DocumentName' ,

                                                                 dataType: 'json' ,                                                                

                                                                  async: false ,

                                                                 success: function (data, status) {

                                                                   

                                                                      if ( typeof (data.error) != 'undefined' ) {

                                                                         if (data.error != '' ) {

                                                                             alert(data.error);

                                                                         } else {

                                                                             alert(data.msg);

                                                                         }

                                                                     }

                                                                 },

                                                                 error: function (data, status, e) {

                                                                      debugger ;

                                                                     alert(e);

                                                                 }

                                                             }

                                                         );

                                                     return [ true , '' , false ];

 

                                                 }

                                             },

                                              //Delete functionality

                                             {

 

                                              }

                                         });

                                       }


//////////////////////////////////////////////////////

This is my web method which is not getting called:

[WebMethod]

public static void InsertDocumentDetails(

HttpPostedFileBase files

)

{

}


Please hot to call web method to upload file in database.