Filter value

Hi All,

Could anyone explain why I can't enter values in filter text box as shown in the attachment.  Here is my script  

     var grid = $("#grid").kendoGrid({
       dataSource: ds,
       height: 250,
       pageable: true,            
       selectable: "row",
       resizable: true,
       groupable: true,
       sortable: true,           
       filterable: true,
       columns: [
               {   title: "col1",  field: "col_1", width: 80  },
               {   title: "col2",  field: "col_2", width: 80  },
               {   title: "col3",  field: "col_3", width: 120 }

       ]
   })

;
TIA