How to set the owner of a Note with insertRecords?

HI,

I'm trying to create notes (in this case against Leads, although I want to do the same for Accounts & Contacts too) through the insertRecords API. I can insert the notes fine, but I can't seem to control the Owner (who the Note shows up as being from), it always shows up as my user (who owns the authtoken)

I've tried setting (as fields in the xmlData)
* 'SMOWNERID' to 'Id' as returned by the getUsers call
* 'email' to the email address of the User

But the note is still attributed to the API authtoken owner.

Is it possible to set the owner of a note when creating it, and if so what field(s) need to be set in the xmlData (or elsewhere)?

The authtoken owner is an Administrator account.

I'm doing:
POST to https://crm.zoho.com/crm/private/xml/Notes/insertRecords?scope=crmapi&authtoken={token-vaue}

With xmlData like this:
<Notes>
<row no="1">
<FL val="entityId">{LeadId-Value}</FL>
<FL val="SMOWNERID">{UserId-Value-of-Desired-Owner}</FL>
<FL val="Note Title">This is the title</FL>
<FL val="Note Content">And this is the body</FL>
</row>
</Notes>