CKeditor Toolbar : AddButton (3.6)

I want to add a custom button to the toolbar. 

Based on the information here : http://docs.cksource.com/CKEditor_3.x/Developers_Guide/Toolbar I have this config.js : 

     config.toolbar = 'MyToolbar';

    config.toolbar_MyToolbar =
    [
        { name: 'document', items: ['Source', '-', 'Save', 'NewPage', 'DocProps', 'Preview', 'Print', '-', 'Templates'] },
        { name: 'clipboard', items: ['Cut', 'Copy', 'Paste', 'PasteText', 'PasteFromWord', '-', 'Undo', 'Redo'] },
        { name: 'editing', items: ['Find', 'Replace', '-', 'SelectAll', '-', 'SpellChecker', 'Scayt'] },
        {
            name: 'forms', items: ['Form', 'Checkbox', 'Radio', 'TextField', 'Textarea', 'Select', 'Button', 'ImageButton',
              'HiddenField']
        },
        '/',
        { name: 'basicstyles', items: ['Bold', 'Italic', 'Underline', 'Strike', 'Subscript', 'Superscript', '-', 'RemoveFormat'] },
        {
            name: 'paragraph', items: ['NumberedList', 'BulletedList', '-', 'Outdent', 'Indent', '-', 'Blockquote', 'CreateDiv',
            '-', 'JustifyLeft', 'JustifyCenter', 'JustifyRight', 'JustifyBlock', '-', 'BidiLtr', 'BidiRtl']
        },
        { name: 'links', items: ['Link', 'Unlink', 'Anchor'] },
        { name: 'insert', items: ['customImage', 'Flash', 'Table', 'HorizontalRule', 'Smiley', 'SpecialChar', 'PageBreak', 'Iframe'] },
        '/',
        { name: 'styles', items: ['Styles', 'Format', 'Font', 'FontSize'] },
        { name: 'colors', items: ['TextColor', 'BGColor'] },
        { name: 'tools', items: ['Maximize', 'ShowBlocks', '-', 'About'] }
    ];
    
    
    config.extraPlugins = 'customImage';

But the toolbar is not changed. It stays as default.