FYI, I'm using a custom handler because I need to insert it into the database. If I remove some of the manual upload and javascript I need and have it use the built in silverlight, I get this error if it helps:
Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB7.4; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E; OfficeLiveConnector.1.3; OfficeLivePatch.0.0; InfoPath.3; BRI/2)
Timestamp: Fri, 14 Jun 2013 21:00:47 UTC
Message: Exception thrown and not caught
Line: 3289
Char: 8
Code: 0
Message: Unhandled Error in Silverlight Application The remote server returned an error: NotFound. at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at UploadPrototype.MainPage.ProcessResponse(IAsyncResult asyncResult)
at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass19.<
InvokeGetResponseCallback
>b__17(Object state2)
at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()
Line: 1
Char: 1
Code: 0
Message: Unhandled Error in Silverlight Application Failed to Invoke: _onSilverlightError. at System.Windows.Browser.ScriptObject.Invoke(String name, Object[] args)
at UploadPrototype.EventManager.SilverlightError(String message, Int32 index)
at UploadPrototype.MainPage.<>c__DisplayClass1f.<
ProcessResponse
>b__18()
Line: 1
Char: 1
Code: 0