ADA4051-1AKSZ/2ARMZ Differential amplifier configuration

Hi, 

I am trying to use the ada4051 in a differential amplifier configuration. Attached below is a schematic of the circuit with the components being used, ltspice schematic , and a graph comparing outputs. In image one, the high and low inputs are from a simple voltage divider circuit which can be seen in the second image. The chart shows the measurements directly from the divider network (orange) and from the differential amplifier (blue). Why does the differential amplifier circuit not see an output till after 1V if the input voltage range is rail to rail?