Common reason #2

You are using the WRONG DNS.
Go to your domain registrar company, find your domain, change the Name Servers to:

Site builder (Pixel Perfect, Responsive or mobile first builder) depending on the region you want to publish your website: 

1. The local region option is recommended for non-global business and you can use these nameservers: 
ns1.l4dns.com - ns2.l4dns.com 
2. If you want to publish and connect your domain to your website using the CDN option (worldwide), you may use the next nameservers: 
ns3.l4dns.com - ns4.l4dns.com
For responsive blog/site, you should use 
ns1.l4dns.com  -   ns2.l4dns.com

Builderall Business
ns3.l4dns.com  -   ns4.l4dns.com

- Cheetah Builder:

ns3.l4dns.com - ns4.l4dns.com 

- Responsive blog builder, WordPress, Magento, Directory Builder, :

ns1.l4dns.com - ns2.l4dns.com ​​​​​​​​​​​​​​

Note: The region selected for the subdomains MUST MATCH the main domain’s region.​​​​​​​
DON`T USE CAPITAL LETTERS!

Common reason #1

Your website is not published.

Go to My Websites > click on the publish button.  

Common reason #3

Your DNS is not yet propagated.

Solution: Go to https://www.whatsmydns.net, insert your domain and check how the propagation is going. It should look like the image below:

Common reason #4

You have an UNDERLINE ( _ ) on your subdomains (only if you did not connect your own domain.)

Solution: Go to Your Websites, find the button "Change Subdomain", remove the underline of your domain:

​​​​​​​Wrong: http://contact_4.builderall.net/my-first-website

​​​​​​​ Right:​​​​​​​​​​​​​​ http://contact-4.builderall.net/my-first-website