header checkbox not show when filtermode header true

[kk]

When showing the filter in header, the header checkbox to select all row not show.
If the filerModel is removed, the haeder checkbox exist.

The object is as follows, any workaround?

  var obj = { width: 700, height: 400,
                filterModel: {  header: true },
                selectionModel: { type: 'row', mode:'range', all:null, cbHeader:true, cbAll:true}, 
                 title: "ParamQuery Grid Example",resizable:true,draggable:true,   pageModel: { type: 'local', rPP: 20 }, };
                      obj.colModel = [
                         { dataIndx: "localstate", maxWidth: 30, minWidth: 30, align: "center", resizable: false,
                             type: 'checkBoxSelection', cls: 'ui-state-default', sortable: false, editor: false,
                             dataType: 'bool',
                             cb: {
                              all: false, //checkbox selection in the header affect current page only.
                                  header: true //show checkbox in header.
                             }
                      },
........
}