Hi Mike. Two things to check. First, is Views security configured so that you have permission to both read and write to that tag? Second, is that tag actively being logged to, meaning, is their a Sender session currently connected to the Receiver of the historian server you are trying to write to? You cannot write back to a tag that is currently being logged to. I typically use the Calcs & Events server to create my manual entry tags, then delete the calculation expression, releasing the Sender service.