I assume that when you save the file in the database, you are saving a path to the file?
The problem is that that's a local path - it's specific to to computer you are trying to save from, and it won't be available on other computers - it's like expecting a file on a USB stick plugged into my computer to be available on yours!
There really isn't a good solution to this: you need to work out a "common" location that all the computers you expect to be using the images can access, and that they all have read and write permissions to a share.
Alternatively, store them in the DB as an SMB path:
and make sure that everybody has the right permissions on all of the shares.
I hate markup! It swallows my double backslash even when disabled...[/edit]