CMA File Overwrite

If I upload a file to my DL.2's using the CMA and the file name already exists in the folder I'm uploading to, it asks if I want to "overwite duplicate file?" I click "yes", but it does not overwite the file. The old file is still there and the new file is not. Even if I delete the old file and then upload the new file, the old file is still there. The only way to get the new file on is to change it's name before uploading it.

This clearly isn't how "overwrite duplicate file?" should work. Is this a known problem? Is there a fix. Thanks.