Error connecting to vCenter in 5.1 environment

I'm installing Orchestrator 5.1 and everything is working EXCEPT registering the vCenter Server Extension.

I get the following error:

Title:

Could not register or update vCenter Server extension

Description:

com.vmware.vim.vmomi.client.exception.SslException: com.vmware.vim.vmomi.core.exception.CertificateValidationException: Server certificate chain not verified

I imported the vCenter certificates using the webclient URL. 

Any advice?