Multicast over NBMA makes my brain hurt

Okay, I must be totally missing the boat here, but I can't get Multicast
over NBMA to work AT ALL.

R2-----\
          -------- R1
R3-----/

All interfaces are physical interfaces with static ipv4 mappings. R1 has
DLCIs to both spoke routers, and spoke routers only have DLCIs to R1. This
is as simple as I know how to get it.

*** R1 ***
interface Serial1/0
 ip address 10.0.0.1 255.255.255.0
 ip pim dr-priority 1000
 ip pim nbma-mode
 ip pim sparse-mode
 encapsulation frame-relay
 frame-relay map ip 10.0.0.3 103 broadcast
 frame-relay map ip 10.0.0.2 102 broadcast
 no frame-relay inverse-arp
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.0
!
ip pim rp-address 1.1.1.1

*** R2 ***
interface Serial1/0
 ip address 10.0.0.2 255.255.255.0
 ip pim sparse-mode
 encapsulation frame-relay
 frame-relay map ip 10.0.0.3 201
 frame-relay map ip 10.0.0.1 201 broadcast
!
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
 ip pim sparse-mode
 ip igmp join-group 229.0.0.2
!
ip route 1.1.1.1 255.255.255.255 10.0.0.1
ip pim rp-address 1.1.1.1

*** R3 ***
interface Serial1/0
 ip address 10.0.0.3 255.255.255.0
 ip pim sparse-mode
 encapsulation frame-relay
 frame-relay map ip 10.0.0.2 301
 frame-relay map ip 10.0.0.1 301 broadcast
!
ip route 1.1.1.1 255.255.255.255 10.0.0.1
ip pim rp-address 1.1.1.1

*** Testing ***
Ping is from R3 to 229.0.0.2, which is joined on R2. The first ping goes
through fine, all others drop until the mroute times out on R1.

---
R3(config)#do ping 229.0.0.2 re 10
Type escape sequence to abort.
Sending 10, 100-byte ICMP Echos to 229.0.0.2, timeout is 2 seconds:
Reply to request 0 from 2.2.2.2, 48 ms.........
R3(config)#
---
Debugs indicate that R2 (subscriber router) is sending a PIM Prune to R1
(the hub/RP) as soon as the first packet is received.  R2 retains the (S,G)
mapping with an incoming interface of s1/0, but the prune message causes R1
to remove S1/0 from the OIL.  Any packets after the first are dropped on R1
due to the olist being null.
I don't understand why the PIM Prune is being generated on R2 for R1 --
isn't that the router that's sending the stream?  Most of all, I don't
understand why something that seems so simple isn't working!
In conclusion, I hate multicast!
Appreciate any help you might be able to provide. =)
Keller Giacomarro
keller.g_at_gmail.com
Blogs and organic groups at http://www.ccie.net