FeatureLayer SaveEdits failing

FeatureLayer SaveEdits failing

I've created a layer which I have bound a DataFeatureForm. Everything is working hunky dory, up to the point where I try to call the layers SaveEdits method in the EditEnded event. When I call this method, the SaveEditsFailed event is raised, returning the following message:

ESRI.ArcGIS.Client.Tasks.ServiceException: Unable to complete operation

The Feature's layer API is saying it takes all the edit crud stuff when I hit it with a browser. also I don't know if it will help, but I am providing the Feature Layer a subset of all the layers Out Fields. Could that also effect this?

Thanks for yoru help!

EDIT: I was able to get the HResult from the exception. HResult = -2146233088