Cannot select unallocated partition for restore

I'm trying to restore an Acronis Backup and Recovery 10 SBS backup to a virtual machine in VMWare fusion for the Mac. I actually have a couple of similar setups and I had no problem with those.

In this instance, I can select the first 2 partitions, but the data partition is unavailable (disabled), although it's unallocated space is larger than the actual data volume. Therefore, I cannot proceed, since the partition is required.

Any ideas?

Thanks,

Andrei