Can't get ZB S2B chips to work

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What steps will reproduce the problem?
1. two xbee shields sparkfun, two zigbee pro s2b one as end/router API device 
and one coordinator API device
2. Mega 2560 or UNO, with or without SoftSerial
3.

What is the expected output? What do you see instead?
Message received on coordinator

What version of the product are you using? On what operating system?
Zigbee Coordinator API 2, firmware 21A7
Zigbee Enddevice API 2, firmware 21A7

Please provide any additional information below.
Have tried to set end device SM=1 and jumper on pin 9to10. No difference.

Original issue reported on code.google.com by [email protected] on 16 Dec 2012 at 11:09