SharedObject - ByteArray

Dear all, I have a problem with a SharedObject remote and flash media server (I'm using Flex). I have to store a custom class in a sharedObject, so I implemented the IExternalizable class in my custom object then I stored it on a ByteArray object. I stored this ByteArray on a remote Shared Object, but when I try to retrieve this data, I receive the error of type coercion failed. Does anybody how I can solve this problem?