There could be many reasons for this.
Please check for the following:
1. Does the VIN VA have access to the VC?
2. Is the above VC configured to use non standard ports for HTTP/HTTPS communication (not 80/443)?
3. Does the VIN VA have access to the ESX hosts that host those VMs?
Have you contacted your sales engineer / PSO regarding this issue?
Is there an SR open on this?
It will be very helpful to get a support package from the VA to analyze what happened, as this is a very general error.