Windows 7: Folder sharing trouble

I have a new Windows 7 x64 laptop connected to my home network (HomeGroup). My Windows 7 x64 desktop PC can see the laptop's filesystem and vice-versa. I've shared the MyDocuments folder on the laptop with everybody (no passwords, full control, made it as promiscuous as I can). I can drag a file from that folder to the desktop PC, but whenever I try to drag anything from the desktop PC to the laptop I'm told, "Destination folder access denied" and "You need permission to perform this action." Any ideas what I'm doing wrong? I know this has been covered many times around here, but none of the threads I've read seem to help. Thanks loads.

You need to make sure your permissions are right. You might have set them for everyone but you didn't specify which permissions you gave them.

NTFS and share permissions systems are completely separate from each other, to access files on a shared NTFS drive they user must have the correct NTFS and the correct share permissions.

Always remember the least invasive permissions will be used

Here is a good tutorial.
Sharing and Permissions