Unable to Create LetsEncrypt SSL on Laravel Forge

I've hosted my app in DO with Laravel forge. And I'm trying to install SSL for my app domain, but I've been getting the following error:

--2018-12-24 07:02:18--  https://forge-certificates.laravel.com/le/463926/676485?env=production
Resolving forge-certificates.laravel.com (forge-certificates.laravel.com)... 104.25.8.32, 104.25.9.32, 2606:4700:20::6819:820, ...
Connecting to forge-certificates.laravel.com (forge-certificates.laravel.com)|104.25.8.32|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘letsencrypt_script1545634938’

     0K ..                                                     26.6M=0s

2018-12-24 07:02:20 (26.6 MB/s) - ‘letsencrypt_script1545634938’ saved [2278]

Cloning into 'letsencrypt1545634940'...
ERROR: Challenge is invalid! (returned: invalid) (result: {
  "type": "http-01",
  "status": "invalid",
  "error": {
    "type": "urn:ietf:params:acme:error:dns",
    "detail": "DNS problem: NXDOMAIN looking up A for www.crusadehimalaya.com",
    "status": 400
  },
  "url": "https://acme-v02.api.letsencrypt.org/acme/challenge/pu7gPisKoSluDK8ekNAlZBjra-KMpCoEoZDzMkVE6Vs/10662604599",
  "token": "GL0QUoKMXrRmUxoPuSDTidXAjaoeFC3MESlPYltCRMo",
  "validationRecord": [
    {
      "url": "http://www.crusadehimalaya.com/.well-known/acme-challenge/GL0QUoKMXrRmUxoPuSDTidXAjaoeFC3MESlPYltCRMo",
      "hostname": "www.crusadehimalaya.com",
      "port": "80"
    }
  ]
})

I've added crusadehimalaya.com as my domain in Laravel Forge site meta and Digital Ocean domain list [1 A Record, 3 NS Record]. As in tutorial video https://laracasts.com/series/learn-laravel-forge/episodes/20 I cannot create SSL certificate.