Failed data binding for dataInput/defaultValue in netui

[I've looked for a way of starting a new topic in these forums without success.
So I'm replying to this similar topic.]

I've inherited a WebLogic project, and I'm having trouble with data binding.

There's a pre-existing JSP using taglibs like this that are working just fine:

  <c:out value=[b]"${regflowConfig.userName}" [/b]/>

I want to add a hidden input like this:

  <netui:hidden dataSource="{actionForm.userName}"
[b]dataInput="${regflowConfig.userName}"[/b]
tagId="userName"/>

But I get in-pagesource errors like this:

[i]   Attribute: dataInput
   Expression: ${regflowConfig.userName}
   Caught exception while evaluating expression
"${regflowConfig.userName}" with available binding contexts
[actionForm, pageFlow, globalApp, request, session, appication, pageContext,
bundle, container, url, pageInput].
    Root cause: com.bea.wlw.netui.script.xscript.IllegalContextStateException:
The context "regflowConfig" could not be found.[/i]

Since the regflowConfig context works fine for the <c:out> tag, I don't
understand this.  Googling for example uses of dataInput with expressions shows
the "${...}" syntax is correct also.

btw, I have a similar problem if I try adding
[b]defaultValue="${regflowConfig.userName}"[/b] to the netui:textBox

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