Multisite subdomain instead of directory issues

I installed wordpress with multisite, but it shown as subdirectory , i dont want my site as subdirectories, i want only subdomains. so i changed code in wp-config define('SUBDOMAIN_INSTALL', false); like define('SUBDOMAIN_INSTALL', true); . after that i could create subdomains. but i was not able to open my subdomains...... please give me a solution to bring my subdomains live..
I already tried several solutions given to me on the forum and did not work, so I was asked to create a ticket.

Let me know if you need FTP access.