I don't see any problem. This is what I did:
On the seed node:
createkeypairs
{
"address" : "1...",
"privkey" : "V..."
}
grant 1... connect,send,receive
On the new node:
multichaind chain@seed-ip:port -initprivkey=V...
multichain-cli chain getinfo
{
...
}
Is this what you are doing? Are you using multichain.conf?