I get the following error message when trying to create new slave site from template. The procedure has worked before, but I did notice that my host (hostmonster) seems to have changed the way it operates in that I am now asked to login to myphpadmin. In any event, I the existing user privileges are set to all and the existing joomla site operates fine.

Create DB error [1044]: Query = [CREATE DATABASE `new_user` CHARACTER SET `utf8`], DB Message = [Access denied for user 'existing_user'@'localhost' to database 'new_database' SQL=CREATE DATABASE `new_database` CHARACTER SET `utf8`]

Can I use the username and password for phpmyadmin to set multisites.cfg.php or must it be the database user?
What else can I do to get the database up and running?
If I create the database before trying the save the slave site, I still get a long list of errors in respect of the table creation authority.
Should I contact the host?

I have contacted hostmonster and to quote them "this will never work".
All databases and usernames must be created through the cpanel.
However, when I do that I now get a 500 server error:
500 - An error has occurred.

JDatabaseMySQL::query: 1142 - GRANT,TRIGGER command denied to user 'existing_user'@'localhost' for table 'jos_users' SQL=GRANT ALL PRIVILEGES ON `existing_user`.`jos_users` TO `new_user`@`url` IDENTIFIED BY 'dbpassword' WITH GRANT OPTION;

It seems to be JMS script cannot be used on shared host?

Here the error that is reported concern the creation of a DB dynamically.
Perhaps you should create the DB with cPanel before using it in JMS Multisites.

If you think that you have created before creating the slave site, review your parameters as you request to create the DB. Perhaps you mispelled a name.

Update: I have now got the slave site to install successfully after having done three things:
1 I upgraded JMS Multisite from 1.2.31 to 1.2.32
2 I turned off all user sharing options (the 3rd tab on the template page)
3 I deleted the database-less new site and re-inputted the parameters
i will have to experiment with another site to see I can found out what went wrong.

As you have mentionned cPanel in previous post, this could be related to the sharing.
When you share extension, you need to have a MySQL user that has all the privileges.
Unfortunatelly, cPanel does not provide All privileges (this is false).
See the tutorial video 0.b slide 35 to see the specific case of cPanel.
You need to add the "create view" and "show view" privileges

Update: I have established that if I turn on user sharing in the template, I receive database errors. Without it the installation of the slave site is successful.
Yes, I am on cpanel. I studied slide 35 but unfortunately my phpmyadmin panel has no Privileges tab. I presume that it may still be possible to create the privileges by running a SQL command but I would have to revert to my SQL references to find out how to do it (can't remember everything!).
Help me out here?