Am able to open documents ,sheets in zoho writer and zoho sheet

When i tried to open ppt or pptx file in zoho show it giving http 400 error .

below is the html code for posting file and data

<form method="POST" action="https://show.zoho.com/remotedoc.im" enctype="multipart/form-data" target="_self" accept-charset="UTF-8"> File : <input type="file" name="content" size="38"> <br/> <input type="hidden" name="apikey" value="myapikey"> <input type="hidden" name="output" value="editor"> <input type="hidden" name="mode" value="view"> <input type="hidden" name="filename" value="mysheet.pptx"> <input type="hidden" name="skey" value="myskey"> <input type="hidden" name="lang" value="[en/fr/de/ja/it...]"> <input type="hidden" name="id" value="12345670000"> <input type="hidden" name="format" value="pptx"> <input type="hidden" name="saveurl" value="[https://xyz.com/docs/save.php]"> <input type="submit" name="submit" value="Open/Edit"></form>  Please help