Grid : features groupingsummary doesn't work extjs 6.5.0 - extjs6.5.1

Question

enter image description hereI am new with Extjs 6, and i am implementing a Grid with groupping summary features, i tried this two examples :
http://examples.sencha.com/extjs/6.5.0/examples/classic/grid/group-summary-grid.html
but doesn't work, i have this problem in my browzer console.
Have someone an idea about this errors?
enter image description here
GET localhost/Geomap2018/feature/groupingsummary.js?_dc=20170104130840 404 (Not Found)
Uncaught TypeError: c is not a constructor
this is the example which i tried: http://docs.sencha.com/extjs/6.2.0/classic/Ext.grid.feature.GroupingSummary.html
Ext.define('TestResult', {
extend: 'Ext.data.Model',
fields: ['student', 'subject', {
name: 'mark',
type: 'int'
}]
});
var grid = Ext.create('Ext.grid.Panel', {
width: 200,
height: 240,
features: [{
groupHeaderTpl: 'Subject: {name}',
ftype: 'groupingsummary'
}],
store: {
model: 'TestResult',
groupField: 'subject',
data: [{
student: 'Student 1',
subject: 'Math',
mark: 84
}, {
student: 'Student 1',
subject: 'Science',
mark: 72
}, {
student: 'Student 2',
subject: 'Math',
mark: 96
}, {
student: 'Student 2',
subject: 'Science',
mark: 68
}]
},
columns: [{
dataIndex: 'student',
text: 'Name',
summaryType: 'count',
summaryRenderer: function (value) {
return Ext.String.format('{0} student{1}', value, value !== 1 ? 's' : '');
}
}, {
dataIndex: 'mark',
text: 'Mark',
summaryType: 'average'
}]
});
var win = Ext.create('Ext.window.Window', {
width: 300,
height: 200,
items: [grid]
});
win.show();

Answer 1

Ext.view.Table.constructFeatures calls Ext.create which in turn calls the following.
feature = Ext.create('feature.' + feature.ftype, feature);
It doesn't look like the feature configuration has any typos, so Ext.create will eventually call the class manager passing the resolved class for the feature.
cls = Manager.get(name);
...
return Manager.getInstantiator(args.length)(cls, args);
From the exception, "c" is "cls" - the feature class. Therefore, I think the class manager is not finding the feature class. Make sure you've added Ext.grid.feature.GroupingSummary to the requires declaration so that the class is loaded and available.