How to address 'ping -I <interface>' failure

Background:
  2 wan interfaces - call them 12.14.16.18 on eth0 (not the issue) and 98.100.102.105 on eth1 (both /29),
  'ping -I 98.100.102.105 google.com' works but 'ping -I eth1 google.com' returns 'From 98.100.102.105 icmp_seq=1 Destination Host Unreachable'

  'cat /etc/iproute2/rt_tables' shows (leaving out commented lines)

     255     local
     254     main
     253     default
     0       unspec
     1       fbr
     3       dsl

  ip rule shows (leaving out default and ipsec)

     10000:  from all fwmark 0x1/0xff lookup fbr
     10002:  from all fwmark 0x3/0xff lookup dsl
     20000:  from 12.14.16.18 lookup fbr
     20000:  from 98.100.102.105 lookup dsl

  ip route show table dsl has (leaving out OpenVPN and other local non-Internet interfaces)

     default via 98.100.102.108 dev eth1  src 98.100.102.105
     98.100.102.104/29 dev eth1  proto kernel  scope link  src 98.100.102.105
     98.100.102.108 dev eth1  scope link  src 98.100.102.105

I'm just beginning to learn about multiple routing tables so I tried the following suspecting it wouldn't work (and it didn't): 'ip rule add from eth1 table dsl' and got 'Error: ??? prefix is expected rather than "eth1" '

What do I need to do to get 'ping -I eth1 google.com' to work?  Thanks for your help.