AD9281 problem

I have a circuit that uses an AD9281

If I connect VREF/2 to both inputs I should get code 128 out.

For channel 1 I am getting 128 + 16 and for channel 2 I am getting 128 + 32

VREFB is 1 volt and VREFT is 2.5 volts

I suspect something wrong wit VREFT as I think it should be 2 volts not 2.5 volts.

Any advice would be appreciated.

VREF is 2 volt exactly.