problem opening an empty ppt presentation (for a presentation creation)

problem opening an empty ppt presentation (for a presentation creation)

I am using remote api to create or edit documents, spreadsheets and presentations.

For editing existing files, no problem.

But for creating new file, I met problems with presentation.

To create new file, I decided to open an empty file (easier to manage with my storage system) and it works fine for spreadsheet and document.

But for presentation, I have an Http 500 error. The parameters I sent to http://show.zoho.com/remotedoc.im are :
id=test.ppt
submit=Open/Edit
skey=<mysKey>
filename=test.ppt
format=ppt
saveurl=<my save url>
output=url
lang=fr
url=<the URL of an empty file>
mode=normaledit
apikey=<my api key>


If I just ommit the url parameter, I have a HTTP 400 error
id=toto3.ppt
submit=Open/Edit
skey=<mysKey>
filename=toto3.ppt
format=ppt
saveurl=<my save url>
output=url
lang=fr
mode=normaledit
apikey=<my api key>


Any idea where it could come from ?

regards
Jacques