Settin Up a Pair of XBees

I am using two XBees Series 2s and am having trouble setting them up to wirelessly program an Arduino. I am following the write-up at http://www.humboldt.edu/~cm19/XBee%20setup.pdf. The associate light on the XBee shield blinks twice per second when the router/end device is attached and once per second if I attach the coordinator. I am using a Sparkfun XBee Explorer, which does not have an associate light. I receive all the correct responses when I enter commands in the terminal. ATND returns nothing and is the only command that doesnÂ’t work. Can you suggest anything I might do to solve this? Thank you for any suggestions you can give.

Ensure both modules are operating on the same PAN ID and channel so they associate.

You might want to try resetting the modules. First on the coordinator issue a ATNR0 and then on the router ATNR0