Files are uploaded, but fail to move into the right directory

Hi,

I'm trying to use WebFM on Drupal 6.x to provide a selected group of users a way to upload files to our web without using FTP. I first tried in a locally installed website and WebFM works fine there. But now I've tried in a true shared hosting service and every time I try to upload a file, it gets uploaded to the temporary directory (/tmp with the default config, also happens defining another private temporary directory), but when WebFM tries to move it to the final destination it fails. In the "Upload file" box I get the message "file_move fail" in red color, instead of the usual "Upload Success" green message.

I've SSHed into the hosting and manually moving files works if I'm their owner (with my account, which obviously is not the one Apache is running, nobody). We have had no problems uploading files using another CMS (eGroupware), so there is a way to upload files to the hosting, and therefore, I think I can't complain our hosting provider.

I'd appreciate any hints to solve the issue.