XBee network discovery in API mode

Hi all,
 

 This is not directly rabbit related (yet)... since for the moment I'm playing with the xbee modules all connected on a windows pc though usb-serial adaptors. I want to play with them and see what's happening with my own eyes :) Then, I'll have some rabbit targets for them.
 

 All in all, I set up a network with 3 modules, one coordinator and 2 routers. Everything works very well (and I tested  A LOT...).
 

 I only have one little problem: the ND command in API mode seems to not work as expected.
 First, in AT mode it works ok. It generates two groups of network info for the two routers, exactly as documented in the manual.
 In API mode however, I'm receiving only one 0x88 frame with the first router info, and a 0xA1 frame with the address of the second router (and two zero bytes at the end that I can only guess what's the meaning)
 

 Here is the first frame (a 0x88 one): (with my debugging messages)
 API Frame received:
 88 01 4E 44 00 23 08 00 13 A2 00 40 B2 49 50 45 54 48 32 33 32 49 4F 34 00 FF FE 01 00 C1 05 10 1E
 AT cmd response: ND
 status: 0
 data:
 23 08 00 13 A2 00 40 B2 49 50 45 54 48 32 33 32 49 4F 34 00 FF FE 01 00 C1 05 10 1E
 NI indicator content:
 address: 2308:0013A20040B24950
 NI: ETH232IO4
 parent: FFFE
 device type: 1
 
 source event: 0
 

 And then the second frame (a 0xA1 one):
 API Frame received:
 
 A1 00 13 A2 00 40 E5 78 C9 F6 20 00 00
 My note here: the address is correct for the second router. The last two zeros may mean something like: no options (first byte) and zero addresses (the second byte) although this is just a guess.
 

 There is more: if I insist of doing ND commands repeatedly, I will get sometimes 0x88 frames with the second router info! But always a SINGLE FRAME, not two.
 

 It seems to me that the ND command in API mode is not very robust. At least I cannot find a good documentation for it (in API mode). In AT mode it seems that it works very well though.
 

 Now, I have two solution:
 1. Switch to AT mode and deal with the ND only in AT mode - that only for the ND command
 2. Just forget about ND - it's somewhat possible in my intended app - although the ND is quite nice to have and more convenient.
 

 Unless someone will make some light about it... :)
 

 Thanks,
 Raimond