trying to route between two openvpn clients

Does anything appear in firewall logs? Can you diagnose exactly where the traffic brakes using tcpdump? What system are you using (linux, freebsd, which version)?

Also try this in the server config (from the OpenVPN documentation):

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client

In order to get my clients talking to each other via the OpenVPN server, I needed to uncomment client-to-client in my config as @kyrisu suggests, but I also had to add topology subnet to my server config:

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0
topology subnet