How can I modify the Notes_Entry ClearQuest field using OSLC 2.0 API? (receiving 409 error...)

I have successfully switched a ClearQuest record from the "Defined" state to the "Investigate" state using the OSLC 2.0 API (using the "Investigate" action).

However, with very similar code, now I am trying to switch a ClearQuest record back from the "Investigate" state to the "Defined" state.  I thought that specifying the "ReDefine" action would be enough, but I am getting a 409 error as well as message "CRVAP0290E CRMUD0061E The field "Note_Entry" is mandatory; a value must be specified.".

I did include a Note_Entry in the XML I have sent out -- so why I am getting this error?

Here is the XML I've sent:

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cq="http://www.ibm.com/xmlns/prod/rational/clearquest/1.0/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:oslc="http://open-services.net/ns/core#" xmlns:oslc_cm="http://open-services.net/ns/cm#">
<oslc_cm:ChangeRequest rdf:about="http://mitelcqw.mitel.com/cqweb/oslc/repo/MITEL/db/MN/record/16777224-34138553">
<oslc_cm:status>Defined</oslc_cm:status>
<cq:Note_Entry>Exprimental note programmatically added by JLCLICQUTILS on state switch...</cq:Note_Entry>
</oslc_cm:ChangeRequest>
</rdf:RDF>

And here is the response I've received back:

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns="http://open-services.net/ns/core#" xmlns:cq="http://www.ibm.com/xmlns/prod/rational/clearquest/1.0/">
<Error>
<message>CRVAP0290E CRMUD0061E The field "Note_Entry" is mandatory; a value must be specified. </message>
<statusCode>409</statusCode>
< details xmlns="http://www.ibm.com/xmlns/prod/rational/clearquest/1.0/">
<invalidFields>
<Note_Entry>
<message>CRMUD0061E The field "Note_Entry" is mandatory; a value must be specified.</message> <currentValue/>
</Note_Entry>
</invalidFields>
< /details>
</Error>
</rdf:RDF>

Can anyone spot something wrong in the XML I've sent out?