Extjs timeFiled 设置时间段 Maxvalue 与 Minvalue

var fp = new Ext.form.FormPanel({
frame:false
,baseCls:'x-plain'
,autoWidth:true
,autoHeight:true
,fileUpload:true
,labelWidth:80
,labelAlign:'right'
,defaults:{
anchor:'100%'
//,msgTarget:'side'
}
,items:[{
xtype:'textfield'
,id:'txtTaskName'
,name:'taskName'
,fieldLabel:'任务名称'
,allowBlank:false
,maxLength:50
,emptyText:'易记的标识，如"2010年1月催费数据"'

},{
xtype:'fileuploadfield'
,id:'txtImportFile'
,name:'importFile'
,buttonText:''
,fieldLabel:'数据文件'
,allowBlank:false
,emptyText:'请选择Excel数据文件'
,editable:false
,buttonCfg:{iconCls:'folder_explore'}
},{
xtype:'textarea'
,fieldLabel:'备注'
,id:'txtRe'
,name:'re'
,maxLength:1000
,height:50
},{
xtype:'checkbox'
,fieldLabel:'预设外呼时间'
,id:'cbSchedule'
,name:'schedule'
,listeners:{
check:function(checkbox, checked){
if(checked) {
Ext.getCmp('txtDate').enable();
Ext.getCmp('txtTime').enable();
}
else{
Ext.getCmp('txtDate').disable();
Ext.getCmp('txtTime').disable();
}
}
}
},{
xtype:'datefield'
,id:'txtDate'
,name:'scheduleDate'
,fieldLabel:'预定外呼日期'
,format:'Y-m-d'
,editable:false
,allowBlank:false
,disabled:true

},{
xtype:'timefield'
,id:'txtTime'
,name:'scheduleTime'
,fieldLabel:'预定外呼时间'
,maxValue:'10:00:00'
,minValue:'07:30:00' 
,format:'H:i:s'
,editable:false
,allowBlank:false
,disabled:true
,increment:30 }]
});红色部分不同通过。这样设置不行吗？