I am trying to set up a grid that would show the groups a user is a member of so that you can select which groups to remove them from. I would like to use the "Checkbox Selection Model" in case there are multiple groups to remove the user from. The problem I am having is being able to actually get the selection that the user has chosen to be able to work with.

Here is the code for the grid with the checkbox selection model and the delete button. When I click on the delete button I would like to return the selection and be able to grab the values in one of the grid cells for each row selected. I just cannot seem to get it figured out. If you need me to supply a json string of data and the store and model code I can do that.

Code:
Ext.define('AdminPortalMVC3.view.Remove_Group_Win', {
    extend: 'Ext.window.Window',
    alias: 'widget.Remove_Group_Win',

    height: 600,
    id: 'Remove_Group_Window',
    width: 1300,
    layout: {
        type: 'fit'
    },
    title: 'Remove Groups',
    titleAlign: 'center',
    modal: true,

    initComponent: function() {
        var me = this;

        Ext.applyIf(me, {
            items: [
                {
                    xtype: 'gridpanel',
                    id: 'Remove_Groups1',
                    title: 'Total Groups Found = ',
                    allowDeselect: true,
                    columnLines: true,
                    emptyText: 'No Groups Found',
                    store: 'Remove_Groups_Store',
                    columns: [
                        {
                            xtype: 'gridcolumn',
                            id: 'Group_Name_ID1',
                            width: 250,
                            dataIndex: 'Group_Name',
                            text: 'Group Name'
                        },
                        {
                            xtype: 'gridcolumn',
                            id: 'Group_Type_ID1',
                            width: 150,
                            dataIndex: 'Group_Type',
                            text: 'Group Type'
                        },
                        {
                            xtype: 'gridcolumn',
                            id: 'Group_Scope_ID1',
                            width: 150,
                            dataIndex: 'Group_Scope',
                            text: 'Group Scope'
                        },
                        {
                            xtype: 'gridcolumn',
                            id: 'Group_DisplayName_ID1',
                            width: 250,
                            dataIndex: 'Group_DisplayName',
                            text: 'Group Display Name'
                        },
                        {
                            xtype: 'gridcolumn',
                            hidden: false,
                            id: 'Group_Description_ID1',
                            width: 400,
                            dataIndex: 'Group_Description',
                            text: 'Group Description'
                        },
                        {
                            xtype: 'gridcolumn',
                            hidden: true,
                            id: 'Group_DN_ID1',
                            width: 350,
                            dataIndex: 'Group_DN',
                            hideable: false,
                            text: 'Group DN'
                        }
                    ],
                    viewConfig: {
                        enableTextSelection: true
                    },
                    selModel: Ext.create('Ext.selection.CheckboxModel', {
                        ignoreRightMouseSelection: true,
                        checkOnly: true
                    }),
                    dockedItems: [
                        {
                            xtype: 'toolbar',
                            dock: 'top',
                            items: [
                                {
                                    xtype: 'button',
                                    id: 'UM_Delete_Groups1',
                                    text: 'Delete Groups',
                                    listeners: {
                                        click: {
                                            fn: me.onUM_Delete_GroupsClick,
                                            scope: me
                                        }
                                    }
                                }
                            ]
                        }
                    ]
                }
            ],
            listeners: {
                show: {
                    fn: me.onRemove_Group_WindowShow,
                    scope: me
                }
            }
        });

        me.callParent(arguments);
    },

    onUM_Delete_GroupsClick: function(button, e, options) {
        var ids = '';
        Ext.each(Ext.getCmp('Remove_Groups1').getSelectionModel().getSelection(), function(row, index, value) {
            console.log('You have chosen group index = ' + index + ' row = ' + row + ' value = ' + value);
            ids = ids + row.data.Group_DN_ID + ',';
        });
        ids = ids.slice(0,-1);
        Ext.Ajax.request({
            url: 'myurl',
            params:{'GroupName':ids},
            success: function(action){
                //Load Store or something here
                console.log('Here are the groups you are deleting ' + ids);
            },
            failure: function(action){
                Ext.Msg.show({
                    title: 'Uh-Oh!',
                    msg: 'Something went wrong here.  Now figure it out!'
                });
            }
        });
    },

    onRemove_Group_WindowShow: function(abstractcomponent, options) {
        var unetid = Ext.getCmp('BINetID_Display').value;
        console.log('Loading the Groups to be deleted');
        var myGroupForm = Ext.getCmp('Remove_Groups1');
        store = Ext.data.StoreManager.lookup('Remove_Groups_Store').load(function(){
            store.proxy.url = '/umgroups/index/Get?UserNetID=' + unetid;
            store.load({
                waitMsgTarget: 'Admin_Portal_VP',
                waitMsg: 'Loading...',
                callback: function(records, operation, success){
                    var mygnGrid = Ext.getCmp('Remove_Groups1');
                    var mygnTotalCount = mygnGrid.getStore().getCount();
                    mygnGrid.setTitle('Total Groups Found = ' + mygnTotalCount);
                }
            });
            console.log('Finished loading the Groups to be deleted');
        });

    }

});
Thanks for taking the time to look at this and hopefully be able to point me in the right direction.