Overnight loopback test and observed data loss!!!

I have currently hooked up several Series 1 Pro modules up to my system and running loopback test. My test setup is a module connected to a main control system (Master) and another two modules to my remote systems (Node 1 & Node 2).

Module Type: XBee-PRO 802.15.4 (Formerly Series 1) - 63 mW, wire antenna
Firmware: 1084

Module profile at the Master:

XBP24_15_4_1084.mxi
FE
0
241
1084
0
[A]CH=C
[A]ID=3332
[A]DH=0
[A]DL=FFFF
[A]MY=0
[A]RN=0
[A]MM=0
[A]CE=1
[A]SC=1FFE
[A]SD=4
[A]A1=0
[A]A2=0
[A]PL=4
[A]CA=2C
[A]SM=0
[A]ST=1388
[A]SP=0
[A]DP=3E8
[A]BD=3
[A]RO=3
[A]D7=1
[A]D6=0
[A]D5=1
[A]P0=1
[A]AP=0
[A]PR=FF
[A]RP=28
[A]CT=64
[A]GT=3E8
[A]CC=2B

Module Profiles at the two nodes:

XBP24_15_4_1084.mxi
FE
0
241
1084
0
[A]CH=C
[A]ID=3332
[A]DH=0
[A]DL=0
[A]MY=1 (& MY=2 for Node 2)
[A]RN=0
[A]MM=0
[A]CE=0
[A]SC=1FFE
[A]SD=4
[A]A1=0
[A]A2=0
[A]PL=4
[A]CA=2C
[A]SM=0
[A]ST=1388
[A]SP=0
[A]DP=3E8
[A]BD=3
[A]RO=3
[A]D7=1
[A]D6=0
[A]D5=1
[A]P0=1
[A]AP=0
[A]PR=FF
[A]RP=28
[A]CT=64
[A]GT=3E8
[A]CC=2B

Usage Scenario:

The Master is polling each nodes every second and each nodes will response back. Approximately 50 bytes of data every 100ms @ 115200 baud rate. Series 1 Pro (RF Date Rate = 250Kbps) bandwidth should be sufficient to support this.

Issue with data loss:

Tested with 115200 baud rate initially and observed data loss. 254 data transmitted and 235 data received on a loopback test. The distance between the Master and the Nodes are one node just on the side of the master and another 30~40m away with a few wall in between. Data loss still happened when I lower the baud rate to 57600. On my wired loopback test, I didn’t observed any data loss.

Any feedback why through the Series 1 module, there are data loss? or is that anything I have neglected in setting the module?