HTTP Error 500 when add an update (Invalid APP or Invalid Data)

Hi,

I'm getting HTTP Error 500 when I try to add an update. I'm getting the following response error:

{ "error" : { "uri" : "http://social.yahooapis.com/v1/errors/500","lang": "en-US","description": "Internal Server Error","detail": "Error parsing request body(Invalid APP or Invalid Data)" }}

I'm using the PHP SDK from Yahoo! Social API SDKs (http://developer.yahoo.com/social/sdk/#php), this SDK uses json son to insert the update and it looks like correct.

{"updates":[{"collectionID":"**************************","collectionType":"guid","class":"app","source":"APP.********","type":"appActivity","suid":"appActivityGrudi-123422153","title":"Grudi publicado","description":"Teste do myGrudi","link":"http:\/\/www.mygrudi.com.br","pubDate":"1249671929"}]}

Can someone help me on this?

Thanks in advance.