Cisco Switching/Routing :: Create A Port Channel That Spans Two Different Nexus 2248TP Switches

I have a router on  which I would like to create a port channel that spans two different Nexus 2248TP switches, and then create a couple subinterfaces on the router's po interface.  I've done this successfully on my primary router, but the config doesn't seem to work on the backup router.  The primary is running IOS 15, while the backup is running 12.4.25d advanced IP.  I do see the trunk come up from the switch side, and my router subinterfaces and po interface show up, however I'm not able to get anywhere from the router.  It's not even able to reach other hosts on the same network.  As soon as I remove the port channel config and use the physical interface and assign the same address used on the port channel interface, everything works as expected and I have connectivity.
 
interface Port-channel21
no ip address
hold-queue 150 in
!
interface Port-channel21.248
encapsulation dot1Q 248 native
ip address 100.100.100.1 255.255.255.0

[URL]