jQuery Grid Plugin - jqGrid

Hi,

I´m trying to set the value of the rule to 0 but it doesn´t take the validation an is able to submit negative values, how can I fix the issue,

Here is the colmodel, what I´m doing wrong?? ... Thanks in advance

 colModel: [
                            { name: 'Id', index: 'Id', width: 60,hidden:true, align: 'left', editable:false },
                            { name: 'Concepto', index: 'Concepto', width: 50, align: 'left', editable:true, edittype: "select"},
                            { name: 'Descripcion', index: 'Descripcion', width: 90, align: 'left', editable:true, editoptions:{size:10}, editrules: { required: true }},                          
                            { name: 'Cant', index: 'Cant', width: 10, align: 'right', editable:true, editoptions:{size:10}, editrules: { required: true, minValue: 0, number: true } },
                            { name: 'Vlr_unit', index: 'Vlr_unit', width: 18, align: 'right', editable:true, editoptions:{size:10}, editrules: { required: true, minValue: 0, number: true  } },
                            { name: 'Vlr_parc', index: 'Vlr_parc', width: 20, align: 'right', editable:false, editoptions:{size:10} },
                         ],