second click on context-sensitive help not working

I have put some links in my app to context-sensitive WebHelp pages. Clicking one of the links the first time works fine. It opens a new browser window (or a new browser tab, depending on browser settings) and displays the correct page.

But then I go back to the app,and click on a second context-sensitive link. Nothing happens. The help window (or tab) doesn't update. No new window or tab is created.

If I kill the first context-sensitive window (or tab) and then go back to the app and click the second link, another new window or tab is opened. So both links are OK. It just seems like once a window or tab is open, the second click doesn't work.

I'm seeing the same problem in IE and Firefox. Thanks.