One way SSL - Certificate not trusted - Server trust store

Hi,
We are getting Certificate not truested exception.

Client - we have created keystore using keytool included all common trusted certificates that comes with jdk. We got certificate not truseted exception then we have added top level root certificate from server, even then we got same certificate not trusted exception.

So on googling, i have read -
"The web service provider (Server) will create a certificate and get it signed by a Certification Authority like Verisign"

So my question is does server has to get their trusted certificates in keystore signed by CA?

Thanks in advance