Custom Property value not shown during runtime for usercontrol

Question

I am creating DBCombo with a property called DBColumnsCols of type SYColumns. SYColumns is a custom class type. SYColumns has three properties whcih are the sub properties for DBColumnsCols. The property is using UITypeEditor for configuring the columns. The three sub properties are populated properly from UITypeEditor form. But when trying to access the DBColumnsCols property during runtime the values are not there. Also in the form designer where the control is used the property's definition is not shown.

I have also used ExpandableObjectConverter for custom property.

Please assist me in identifying the cause of the issue.

The DBColumnsCols property definition is mentioned below:

[DefaultValue(""), DesignerSerializationVisibility (DesignerSerializationVisibility.Content),Browsable(true)]
[TypeConverter(typeof(ExpandableObjectConverter))]
[EditorAttribute(typeof(FormEditorCombo), typeof(UITypeEditor))]
public  SYColumns DBColumnsCols
{
    get
    {
        return _syCols;
    }
    set
    {   
        _syCols = value;
        if (_syCols != null)
        {
            if (_syCols.ColsCount > 0)
            {
                if (_syCols.ColNames != null && _syCols.ColHeaderText != null)
                {
                    //MessageBox.Show("Setting DBCOLUMNSCOLS");
                }
            }
        }
    }
}