Can you elaborate a little bit? I know there is a place where you can add an attachment via web, so are you seeing that? It should be under the detail tab of the bug you're working on.
If you just don't see it at all, then I don't know, might be time to call Seapine. If you can see it but can't upload files, then I would probably take a stab at it being a security setting or something server-side. I really couldnt' say for certain though.