Accessing https webdev resources

I'm having some issues accessing a webdev resource I set up on another server. If I force https, I run into an error which reads like this:

sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

If I don't force https, I'm able to see everything fine. How can I access this resource while maintaining https? Does an additional certificate need to be added some place or another?