404 error on subdomain, Multisite install

I am a WordPress novice. We have a site for sharing information about a sport. We added Multisite so we could enable clubs to have their own site as a subdomain of ours. (We are hoping to have something like edublogs, but don't anticipate reaching that size.) The multisite conversion seems to have worked and I have the dashboard to create and view our other sites. I have set up wildcard subdomains per the instructions provided by JustHost. When I create a subdomain, I get the prompts and responses indicating the subdomain has been created. When I attempt to access the dashboard of the subdomain, I get a 404 error. If I attempt to access the subdomain URL, I get a message from JustHost saying there is no content.
Here are the contents of the .htaccess file:
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

Thanks for your time and consideration!