Not getting proper range in xbee pro sb2...!!

Hello everyone...

i am working on one project which capture data at remote site and send it to central room. for that purpose i choose XBEE S2 in first stage. my circuit contain two section TX and RX. Each side i use micro controller for process data before use. i just want to remove wire and make it wireless.

my problem is that...

after making my circuit i test range of XBEE S2 and i got near by range as per datasheet. but it is not enough in my project so i decide to use pro module. So i purchase XBEE PRO S2B for long range. after configuration of pro xbee when i attach it with circuit instead of XBEE S2. i am getting signal from one xbee pro sb2 to another xbee pro sb2. but when i test its range its 1/4 of XBEE S2. i can't understand why its happen. i already test some problem reason such as...

1. i provide proper power to xbee pro s2b from 1 amp. SMPS followed by 3.3v voltage regulator.

2. i already select PL value as "4" which is highest among all.

3. also boost mode is enable.

please help me to solve my problem...!

Thanks
bhargav shankhalpara