I have signed for an SSL Certificate (Quick SSL Premium) from Geotrust by my VPS provider (1&1). I, did exactly what it is indicated [here](https://knowledge.geotrust.com/support/knowledge-base/index?page=content&id=SO15167), I added all of the directives at my subdomain's Virtual Host file, but the SSL Certificate seems to be untrusted. What are the possible reasons for that?

I run Ubuntu 10.04 Lucid Lynx with Apache2 and mod\_ssl enabled