also there is another problem: i created a "whole shared" slave site (www1.mydomain.com) but when i go there from www.mydomain.com i need to relogin.

so if i create slave 1a , slave 1b... i will need to relogin them also

Concerning the SQL "command denied to user" as it is mentioned, the reason is that your MySQL user don't have the privilege to share the table.

You have to grant the MySQL and give it more privileges.
If you are using a cPanel tool to manage the MySQL user permission, they have a bug in cPanel that require an action of your hosting provider to grant you MySQL user.

You can find in the forum similar replies to the similar question.
So contact your hosting provider support if you are using cPanel.

If you have your own dedicated server and have for example WHM, you can go directly in the PHPMyAdmin to change the permission of the MySQL user.

my user has all these privileges:

SELECT CREATE
INSERT ALTER
UPDATE DROP
DELETE LOCK TABLES
INDEX REFERENCES
CREATE TEMPORARY TABLES
CREATE ROUTINE

i have reseller account. can i do anything else to change privileges?

i changed some privileges from mysql database. i hope it works..

This is not enought.
You need also permission to create view and show view that is not in your list.

ok at last i could do it. i copied and pasted 41 "create view" command one by one to the database and it is ok now. subdomain with shared users are created.

but there are still problems.

1. (the most important one) if a user clicks subdomain.domain.com while he is logged in www.domain.com, he needs to relogin to subdomain.domain.com. i don't want to log in twice. is there a solution for this? if there is not, most probably, i will not use the extension.

2. my slave site is: www1.mydomain.com. can anybody give an idea about how to redirect www.domain.com to www1.domain.com? with sh404sef's 301 redirect features?

3. i manually gave command "create view" for 41 tables. what if in jomsocial's new releases contain new tables? will it be sufficient to manually give the command "create view"?