problem when creating message using API

problem when creating message using API

I'm trying to create message using such post:
http://projects.zoho.com/portal/yoxel/api/private/xml/message/add?apikey=[apikey]&ticket=[ticketid]&enctype=multipart/form-data&projId=15301e67103a3795d91db262dbc69d00b3711e3d6848763c&mesgtitle=new+subject&mesgbody=test+message+import&mesgcat=Yoxel-Zoho+Integration&uploadfile=&toaddr=

<error><code>6832</code><message>Input Parameters are Incorrect</message></error>

what am I doing wrong? I'm sure that projectId, ticket, apikey are correct, because they works in other requests.

(maybe there is problem with category name: "Yoxel-Zoho Integration", maybe this value isn't correctly passed? is there way to rename message category?)

thanks
mariusz