GoDaddy, DNS Propagation: nameservers did not respond

Hello

I have a droplet which have a domain and I want to add another domain. I bought the new domain from GoDaddy. I’ve set the nameserver to ns1.digitalocean.com, ns2.digitalocean.com, ns3.digitalocean.com. But i’ve got a problem, it takes very long to propagate DNS. I’ve test my domain on intodns.com and it this are errors I found

• ERROR: One or more of your nameservers did not respond: The ones that did not respond are: 173.245.58.51 173.245.59.41 198.41.222.173
• Mismatched NS records: WARNING: One or more of your nameservers did not return any of your NS records.
• ERROR: Looks like you have less than 2 nameservers. According to RFC2182 section 5 you must have at least 3 nameservers, and no more than 7. Having 2 nameservers is also ok by me.
• Missing nameservers reported by your nameservers : You should already know that your NS records at your nameservers are missing, so here it is again:

ns3.digitalocean.com. ns2.digitalocean.com. ns1.digitalocean.com.

Can anyone tell me what is the source of the problem and how to solve it? I’m new to DigitalOcean

Thank You