Aggregator routing for a DigiMesh network (AG command)

Hi everyone,

I am having some trouble routing a DigiMesh network. I am using three XBee-Pro 900HP 200K modules in API mode (latest firmware 8075), and would like to try extend the range of my network by using one of the modules as an intermediate between an aggregator and another sender. I have tested the communication distance, and so I have positioned the far sender outside of communication distance with the aggregator, and the intermediate node in between.

From my understanding, routing can be done using the AG command, so I have been sending an AT.AG.FFFF command using XCTU on my aggregator node (both the sender and intermediate have DH/DL of 0xFFFF). However, I am not getting the expected results that the datasheet claims:
-the address of the intermediate node DOES update to the MAC address of the aggregator, but there is no aggregate addressing (0x8E) frame sent back
-the far sender does not receive any frame at all, and none of its parameters were updated (shouldn’t the DH/DL of the sender be set the MAC address of the intermediate?)

Does anybody have any idea what I could be missing? The documentation on the AG command isn’t very clear. I’ve also tried to follow the “Build and experiment with a DigiMesh network” lab on the DigiMesh Kit User guide, but it hasn’t worked for me. Any help would be greatly appreciated - thanks!