hi,
From the problems other users have had when designing the INA126 for single supply operation, when using a bridge which gives a CMV of Vs/2 it will not work as required.
If you do use an Offset voltage source for Vref, ensure that its a low impedance source.
As I posted earlier I use a MCP6002 R2R after a AD623 [ single supply IA] to provide the low impedance Vref and also to increase the Vout range of the IA from ~ +0.2V +3.5V to 4.9V.
I small Offset in Vo of the IA is required IF your bridge signal can swing slightly negative.
Without some level of Offset you will not show the true Zero output point of the bridge.
What are you weighing.?
E