I have 2 droplets, I added VPS to the second one when it was created. I just added VPS to my first droplet by following the directions from Digital Ocean. However, I cannot SSH into either droplet from the other.

DROPLET 1:
eth1 Link encap:Ethernet HWaddr 04:01:1b:fe:82:02
inet addr:10.128.129.210 Bcast:10.128.129.255 Mask:255.255.255.0
inet6 addr: fe80::601:1bff:fefe:8202/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:32 errors:0 dropped:0 overruns:0 frame:0
TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1596 (1.5 KB) TX bytes:578 (578.0 B)

DROPLET 2:
eth1 Link encap:Ethernet HWaddr 04:01:1f:bc:17:02
inet addr:10.128.151.154 Bcast:10.128.255.255 Mask:255.255.0.0
inet6 addr: fe80::601:1fff:febc:1702/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5784 errors:0 dropped:0 overruns:0 frame:0
TX packets:35 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:312556 (312.5 KB) TX bytes:1826 (1.8 KB)

From droplet 2, when I use ssh root@10.128.129.210 to access droplet 1, I receive the error:

ssh: connect to host 10.128.129.210 port 22: No route to host

And, from droplet 1, when I use ssh root@10.128.151.154 to access droplet 2, I receive the error:

ssh: connect to host 10.128.151.154 port 22: Connection timed out

What am I missing?