Also look at this from the datasheet:
Connecting VREFOUT (pin 4) to one of the four available
reference voltage pins (VREFBG, VREF2.5, VREF5, or VREF10)
provides an accurate voltage source for bridge applications.
The datasheet shows pins 4&16 shorted (VREF10).
I think you should try VREF5 (jumper pins 4&15) after reading this:
I have 2 load cell parts, one for 1kg and the other for 200kg. The 1kg load cell works good with pins 4&15 shorted, but the 200kg load cell gets the precision reference to drop a little.