jdMorgan - 2:50 pm on Sep 1, 2010 (gmt 0)
No bother. This just illustrates the difficulty we have here of trying to get *all* the information needed to provide good answers -- Server type, URL-space layout, file/directory layout, subdomain-creation method used (e.g. Control Panel versus "manual/.htaccess"), content-negotiation, "applications" in use (e.g. WordPress, etc.) -- all of these factors can affect the proper solution...
This is not to mention the need for good "problem reports" that include the specific URL that is causing a problem, the expected results of requesting that URL, the actual results of requesting it, and a description of how the actual results differed from the expected results... It's really hard to figure out some problem without all of the above information.
In this case then, it seems that the problem was that the test environment differs from the production environment. Over the long term, you may wish to address that problem so that when you test on your local test machine, you can be sure that the tested code (whether .htaccess or scripts) will work on your 'live' server.