Hello ooooosh, and thanks for your question.
It looks like your subdomain isn't setup in CloudFlare which is who it looks like you're using as your name servers.
I took a look at CloudFlare's managing DNS records post, and if you read from the Subdomains not working on CloudFlare section you should see this:
If a subdomain on your site isn't working, the most common issue is that you didn't add the subdomain to your zone file when you configured the domain. If you are missing a subdomain called "blog", which translates to blog.yourdomain.com, then you simply need to add the missing record as an A record or CNAME.
A record has to point to a server IP address:
Hope that helps, please let us know if you had any further questions at all.
- Jacob