jQuery Grid Plugin - jqGrid

If I use the search toolbar in jqgrid 4.0.0, and I have a colModel with different name and index…

example:

colModel :[
          {name:'codRole', index:'COD_ROLE', width:55, editable:true},
          {name:'desRole', index:'DES_ROLE', width:90, editable:true}
        ],

(for example because I have a "codRole" json property but a COD_ROLE field to order by on DB)

…the search toolbar doesn't work: the "codRole" search parameter is not sent via GET to the server. If I change the index from COD_ROLE to codRole (so, name and index became equals), the search parameter is sent.

Any idea? Thanks.