unable to get local issuer certificate

I use the “COMODO SSL Analyzer” to analyze certificate of website “vpn.mosaiq.com”.
And I found warning message “unable to get local issuer certificate”.

Trusted by Microsoft? No (unable to get local issuer certificate) UNTRUSTED
Trusted by Mozilla? No (unable to get local issuer certificate) UNTRUSTED

https://sslanalyzer.comodoca.com/?url=vpn.mosaiq.com

How can I fix it?

You’ve hit a very common problem as it looks like your site is not presenting any CA certificates. Browsers (clients) use CA certificates to chain up to Trusted Root authorities and since there is no path presented by your server, systems will most likely not trust your certificate and browsers will throw warnings to users.

Its probably a good idea to reach out to us either by calling us or reaching out to us in a support ticket, which can be submitted via https://support.comodo.com