I have a Grid with GridFilter and when I show for the first times the grid it's work all fine.
If I close the grid and after I reopen it the GridFilter doesn't appears. Why?

The code is:

WINConsulente_GRID = Ext.extend(Ext.grid.EditorGridPanel, {
plugins: [new Ext.ux.grid.GridFilters({
{type: 'string',dataIndex: 'cod'},
{type: 'string',dataIndex: 'username'/*,disabled: true*/},
{type: 'string',dataIndex: 'ragione_sociale'},
{type: 'string',dataIndex: 'telefono'},
{type: 'string',dataIndex: 'fax'},
{type: 'string',dataIndex: 'email'},
{type: 'string',dataIndex: 'website'},
{type: 'string',dataIndex: 'ref_nome'},
{type: 'string',dataIndex: 'ref_cognome'},
{type: 'string',dataIndex: 'ref_telefono'},
{type: 'string',dataIndex: 'ref_cellulare'},
{type: 'string',dataIndex: 'ref_email'},
{type: 'string',dataIndex: 'indirizzo'},
{type: 'string',dataIndex: 'cap'},
{type: 'string',dataIndex: 'frazione'},
{type: 'string',dataIndex: 'localita'},
{type: 'string',dataIndex: 'provincia'},
{type: 'string',dataIndex: 'cod_ateco'},
{type: 'string',dataIndex: 'desc_ateco'},
{type: 'string',dataIndex: 'cod_inail'},
{type: 'string',dataIndex: 'sede_inail'},
{type: 'string',dataIndex: 'iscrizione_inail'},
{type: 'string',dataIndex: 'pers1'},
{type: 'string',dataIndex: 'pers2'},
{type: 'numeric',dataIndex: 'pers3'},
/*{type: 'list',dataIndex: 'size',options: ['small', 'medium', 'large', 'extra large'],phpMode: true},*/
{type: 'date',dataIndex: 'data_creazione',beforeText: 'Prima del', afterText: 'Dopo il', onText: 'Il' },
{type: 'boolean',dataIndex: 'attivo'}