Dirty property value persist problem

Hi,

I created a custom control, and encountered a dirty property value
persistence problem.
I created a property with a custom class type, call SQLSettings which
holds the SQL connection parameters, the class as follows:

public sealed class SQLSettings
{
private string serverName;
.......

public SQLSettings()
{
this.serverName = string.Empty;
......
}

[NotifyParentProperty(true)]
public string ServerName
{
get
{
return this.serverName;
}
set
{
this.serverName = value;
}
}
...................

And, I also created an mapping TypeConverter and UITypeEditor classes
to handle the design-time founctinality. The property I created in my
conbtrol as follows:

[BrowsableAttribute(true)]
[CategoryAttribute("Behavior")]
[BindableAttribute(true)]
[NotifyParentProperty(true)]
[EditorAttribute(typeof(SQLSettingsUITypeEditor),
typeof(UITypeEditor))]

[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
[TypeConverter((Type)typeof(SQLSettingsTypeConverter))]
[PersistenceModeAttribute(PersistenceMode.InnerProperty)]
public SQLSettings SQLSettingsData
{
get
{
return this._sqlSettings;
}
set
{
this._sqlSettings = value;
}
}

They all works fine when first set value to this property, I can see
the persisted data showed in .aspx file. When I go back to design view
and update the property value via my UITypeEditor, I can see the value
already updated in VS.NET properties browser. But when I turn to see
..aspx file in code view, I didn't see the dirty property value updated
in .aspx file. When I turn to design view, the updated property value
is lost, it remain keep the first persisted value.

How about to solve this problem? Any idea?
Thank you for your kindly help.