IncludeFrom editing strange behavior

[Cal]

I have been following your guide here : http://www.smartclient.com/smartgwte...ml#includeFrom

and so far I have the following two fields in my datasource:

<field name="sCode" foreignKey="LP.lpCd" displayField="sName" editorType="ComboBoxItem"></field>
<field name="sName" includeFrom="LP.lpNm" hidden="true"></field>

I have the following ListGridField

lgfSNm = new ListGridField("sCode", "S");

The display values show fine. However when it comes to editing them the entire drop down is empty and if I select an empty line in the drop down it populates a value (a primary key) and then shows the value in the list grid for a few seconds and then changes to the appropriate display field.

Why is this happening, Why can I not see the values?

(Please see attached image for the drop down values I receive...).