404 error for wikimedia index.php

Hi,
I'm running Omeka at itranscribe.com.au and would like to install Mediawiki for a transcription project for Queensland State Archives. The problem is, when I run index.php from a browser, I get a 404 page error. All the mediawiki files are in directory itranscribe.com.au/wikimedia/w and I can access other files within the directory from a browser (e.g. image files). I've tried the Mediawiki email list for help, to no avail. Can anyone here please help?
Thanks,
David

My first guess is that Mediawiki is in a subdirectory of Omeka, which would confuse the url rewrite URLS. Could you describe exactly where Omeka and mediawiki are installed in the directory structure.

Also, are you using Scripto for this?

Spot on! Thanks for that.
And yes, we're using Scripto.
Thanks,
David

Well, trying. I'm not sure how to upload and transcribe documents yet ... very long and slow learning curve!