You need to put the two ip addresses onto different interfaces. The two VSD groups are used on the same interface when you have addresses in the same subnet that can be used for failover on that specific interface. This would be where the traffic for that link will go when the primary VSD group device fails.
In your case you have only a /30 single link so there can be no failover for that interface and thus both have to be on differerent interface numbers on the two devices and have no partner interface for failover.
