title: Kendo Grid does not aggregate
body: <p>I'm using Kendo UI Complete v2013.2.918, trying to show a grid with aggregates by many columns related to one group column, the aggregates is only summing the latest row, I follow the examples on the kendo page and it looks the same but is not doing the sum. Any idea what is the issue?</p>
  
  <p>this is my code: </p>
  
  <pre><code>detailGrid = $("#details_paginated_grid_table").kendoGrid({
  
  columns: [
      { field: "CallDate", title: translate('DATE') },
      { field: "CallTime", title: translate('TIME') },
      { field: "From", title: translate('FROM') },
      { field: "Destination", title: translate('DESTINATION') },
      { field: "MaskedCalledNumber", title: translate('DIALNUMBER') },
      { field: "CallType", title: translate('CALLTYPE'), groupHeaderTemplate: "Name: #= value # total Call Type: #=count#" },
      { field: "CallDurationDisplay", title: translate('MINUTES'), footerTemplate: "Total: #=sum#", groupFooterTemplate: "Minutes: #=sum#", aggregates: ["sum"] },
      { field: "CallRateDisplay", title: translate('RATE'), footerTemplate: "Total: #=sum#", groupFooterTemplate: "Rate: #=sum#", aggregates: ["sum"] },
      { field: "LongDistanceChargeDisplay", title: translate('LD'), footerTemplate: "Total: #=sum#", groupFooterTemplate: "LD: #=sum#", aggregates: ["sum"] },
      { field: "PktDtVolDisplay", title: translate('DATA'), footerTemplate: "Total: #=sum#", groupFooterTemplate: "Data: #=sum#", aggregates: ["sum"] },
      { field: "TotalChargesDisplay", title: translate('TOTAL'), footerTemplate: "Total: #=sum#", groupFooterTemplate: "Charges: #=sum#", aggregates: ["sum"] }                                                
  ],
  
  dataSource: {
      data: [],
  
      group: {
          field: "CallType",
          aggregates: [
              { field: "CallDurationDisplay", aggregate: "sum" },
              { field: "CallRateDisplay", aggregate: "sum" },
              { field: "LongDistanceChargeDisplay", aggregate: "sum" },
              { field: "PktDtVolDisplay", aggregate: "sum" },
              { field: "TotalChargesDisplay", aggregate: "sum" },
              { field: "CallType", aggregate: "count" }
          ]
      },
  
      aggregate: [
          { field: "CallDurationDisplay", aggregate: "sum" },
          { field: "CallRateDisplay", aggregate: "sum" },
          { field: "LongDistanceChargeDisplay", aggregate: "sum" },
          { field: "PktDtVolDisplay", aggregate: "sum" },
          { field: "TotalChargesDisplay", aggregate: "sum" }
      ]
  },
  //sortable: false,
  scrollable: false,
  //pageable: false,
  groupable: true,
  height: 300,
  </code></pre>
  
  <p>});</p>
  
  <p>Here an screenshot about the aggregates:</p>
  
  <p><img src="https://i.stack.imgur.com/QE8nT.png" alt="enter image description here"></p>