Can't access a local network share (folder) from a window computer

On the Ubuntu 14.04 computer:
- open a folder in Nautilus
- right-click on a subfolder
- select "Local Network Share"
- Check all the checkboxes: "Share this folder", "allow others to create...", "guest access"
- to the prompt whether to allow Nautilus to modify permissions automatically, say yes
- save.

From a window computer connected to the same local network:
- go to Network
- the Ubuntu computer is listed. Double click it
- double click on the folder that you have shared before

Expected: should be able to open the folder
Observed: window gives error: access denied.

I have another shared folder within the same filesystem in the same disk in the same computer, which I created ages ago, and that one works fine. All the settings are apparently identical.

Do I perhaps need to reboot (or restart the samba server in some way) for the changes to be effective? If that is the case, it's a bug too.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: samba 2:4.1.6+dfsg-1ubuntu2.14.04.2
ProcVersionSignature: Ubuntu 3.13.0-34.60-generic 3.13.11.4
Uname: Linux 3.13.0-34-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Sep 8 13:09:42 2014
InstallationDate: Installed on 2013-10-11 (331 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
NmbdLog:

SambaServerRegression: Yes
SmbConfIncluded: Yes
SmbLog:

SourcePackage: samba
UbuntuFailedConnect: Yes
UpgradeStatus: Upgraded to trusty on 2014-05-24 (106 days ago)