How to create a new document with writer API

How to create a new document with writer API

Hi, I'm developing a web application with zoho writer api.

If I try to edit an existing document with this html code all works thine:
<form method="POST" action="http://export.writer.zoho.com/remotedoc.im?apikey=xxxxxxxxxxxxxxxxxxxxxx&output=editor " enctype="multipart/form-data" >

<input type="file" name="content">
<input type="hidden" name="saveurl" value="http://www.test.it/save.php">
<input type="hidden" name="id" value="12345678">
<input type="hidden" name="format" value="doc">
<inpuy type="submit" value"Edit" name="submit">

</form>








But I can't create a new document, this code don't work:
<form method="POST" action="http://export.writer.zoho.com/remotedoc.im?apikey=xxxxxxxxxxxxxxxxxxxxxx&output=editor">

<input type="text" name="filename" value="test.doc">
<input type="hidden" name="saveurl" value="http://www.test.it/save.php">
<input type="hidden" name="id" value="12345678">
<input type="hidden" name="format" value="doc">
<inpuy type="submit" value"Create" name="submit">


</form>







       



I get the follow error: "WARNING=File Extension not supported RESULT=FALSE ERROR_CODE=1842"


Can someone help me?!
Thanks