Windows users having problems coecting to an Ubuntu-based SAMBA server

I'm setting up a Samba file server on Ubuntu server 16.04 and wish to access shared folders on Windows 7 and Windows 10 PCs.

I can access any shared folder when alexr is the valid user defined in smb.conf, but I cant access the samba network using Bek's credentials. Windows gives me the following msg when I try to access through RUN \nework location:

…Bek is not accessible. You might not have permission to use this network resource...Multiple coections to a server or shared resource by the same user, using more than one user name, are not allowed. Discoect all previous coections…and try again.

The above error msg has 2 parts. Either user Bek doesn’t have permission or there are multiple coections which are not allowed. I’m not sure which is my problem.

The following screen shots are from smb.conf showing shared folder settings, and the output of listing samba users with pbedit. Thanks for any help in advance.