Stuck: Can't scan to network folder no matter what I do!

[zenpicker]

I'm at my wits' end here...I hope some kind soul can help.

I've struggled in the past to get the Scan to Network Folder feature to work, but finally did. Now I've got a new Macbook Air and have mirrored my old world onto it, but the scan to folder thing is broken. Here's the state of play:

• Manual IP address assigned to the Air - 192.168.1.252
• /Dropbox/Scans destination folder created under admin account (mine - "edward")
• File sharing set read/write for Everyone and Admins
• File sharing confirmed Read/Write for the Scans folder and subfolders via System Preferences. The Sharing applet says: "Other users can access shared folders on this computer, and administrators all volumes, at smb://192.168.1.252" - so, IP address is confirmed correct and SMB is being used.
• On the printer's EWS, the scan destination is set up as: \\192.168.1.252\Dropbox\Scans; it actually used to be \\192.168.1.252\edward\Dropbox\Scans, but after reading various posts it appears that that was incorrect (though it worked!). Just to double-check, if I copy the path straight from one of the files in the Scans folder I get:  /Users/edward/Dropbox/Scans. So that looks right.
• Have tried with and without specifying login credentials in the EWS scan-to-folder setup.
• The Save and Test on the EWS, as well as any attempt at scanning to the folder from the printer, fails.

I cannot, for the life of me, figure out what's wrong. I remember the initial setup of this feature was a nightmare, but the settings I arrived at finally did work, and I haven't changed anything on the printer EWS side...so something must not be quite right on the Mac side. I would so appreciate any insight anyone has. I am completely stumped! Thanks in advance.