RTF to PDF save is not working

RTF to PDF save is not working

We are using coldfusion to post an http request. We pass the hidden form fields as described in the documentation:
the code follows
<cfhttp url="https://exportwriter.zoho.com/remotedoc.im" method="post">
<cfhttpparam type="formfield" name="url" value="https://www.oururl.com/Payment_Plan_Template.rtf">
<cfhttpparam type="formfield" name="apikey" value="our API Key">
<cfhttpparam type="formfield" name="output" value="url">
<cfhttpparam type="formfield" name="mode" value="normaledit">
<cfhttpparam type="formfield" name="filename" value="Payment_Plan_Template_3.pdf">
<cfhttpparam type="formfield" name="lang" value="en">
<cfhttpparam type="formfield" name="id" value="12345678">
<cfhttpparam type="formfield" name="format" value="pdf">
<cfhttpparam type="formfield" name="saveurl" value="https://www.oururl.com/save_doc.cfm">
</cfhttp>

This code generates the following error:
RESULT=FALSE ERROR_CODE=1842 WARNING=Imported file extension not supported

Now, according to the documentation the "format" parameter defines the output format and "pdf" is allowable.  Also, the filename parameter is passed to the postback page "save_doc.cfm", but we never get there because the zoho writer is throwing the above error on post.

We realize that the Export control exports the document to a pdf, but then you have to interact within the browser to save the file.  what we were expecting was that the "Save" button would write out the file to pdf. Naturally, the file would have to be treated as a binary file, but why not?

Bill