unavailable in current context

I'm doing an AJAX refresh and I want to show the error message if the date is invalid.  I'm marking the value as invalid, but the message isn't showing and I can't check if the value is getting sent through because it is unavailable.

How do I make this work?

Hi PJ,

Did you Ajax refresh the Widget after setting it invalid?

I did get the code to work, don't remember the issue, however, I am still confused about why I can't see the values in OS.

It depends from case to case why certain values may be marked as "unavailable". For example, in the Preperation the Screen Widgets aren't available, since they haven't been initialized yet (first the preperation runs, then the Screen is initialized). Other cases are when the compiler has optimized certain things (for example, the Count of a query will not be available if you haven't explicitly referenced it). And then there's the bugs: if you have an Expression that uses parentheses, the Debugger will try to evaluate a Variable including the opening parenthesis.