Can you describe the symptoms in more detail? Is it so that the Write simply appears to be ignored?
Note: If so, this could be due to an error during writing. In Live Bindings, such errors are not, by default, displayed anywhere; you need to create another binding, set the MappingKind to ErrorMessage or a similar result property, and bind it to e.g. another textbox, or a tooltip. There are examples of that in the UALiveBinding project.

A common problem when writing in OPC-UA is that the servers are *not* required to convert the incoming values to the type of the node/attribute. Writing e.g. a text to an integer attribute will then fail; but there are less straightforward cases that fail as well: E.g. there are many types of integers (Int32, UInt32, Int16, UInt16, etc.), and often the type needs to be matched precisely, too. It is quite likely that this is your problem. It can be resolved by properly setting the ValueTypeCode property in the binding editor.

Best regards