How can I enable the file upload permission? - actionscript-3

Question

I'm trying to upload images generated in my Flash application to an album on Facebook. This was working earlier in the year, but revisiting the code I now get the following OAuthException:
(#324) Requires upload file
I am using the most recent version of the ActionSccript Facebook API. The setup works like this:
First I do the authentication check with PHP to ensure users have granted permission before having to wait for the Flash to load. I'm requesting the publish_stream and user_photos permissions. The access token comes back correctly.
Once the user is authenticated the Flash is loaded and performs its own initialisation, passing fileUpload=true as part of the init object:
var initObject:Object = {
channelUrl : "myChannelURL.html",
fileUpload : true
}
Facebook.init(
'myAppID',
myCallbackFunction,
initObject,
myAccessToken
);
This seems to work as expected, the callback receives the uid of the current user.
At the end of my application I POST a Bitmap object to a predetermined album:
Facebook.api(
albumID+"/photos",
onImagePost,
{
message:"",
image:new Bitmap(myBitmapData),
fileName:''
},
URLRequestMethod.POST
);
At this point Facebook returns a 400 response:
"error": {
"message": "(#324) Requires upload file",
"type": "OAuthException"
}
What more do I need to do to ensure that this permission is being included?

Answer 1

It turns out that this was not a permissions error at all. Since I last deployed this code Facebook have tightened up their restrictions a bit, and the fileName parameter passed as part of the api call can no longer be an empty string. Simply passing any old text as a file name fixes the problem.
Facebook.api(
albumID+"/photos",
onImagePost,
{
message:"",
image:new Bitmap(myBitmapData),
fileName:'FILE' // required to be non-empty
},
URLRequestMethod.POST
);

Answer 2

Im not sure if this is a solution that can be translated into the Actionscript SDK... But, with the PHP SDK there is a method inside the facebook SDK that is called setFileUploadSupport - try looking in the code for a place to set that parameter to true.