AD8253 input current


I use ADIsimPE to simulate AD8253. From the datasheet, the input current should be <50nA. However, from simulation I see ~8uA current goes into the amplifier. I'm wondering is it realistic? How come a CMOS opmap has such large input current?

For a very basic test, vinp=vinm, I intentionally use R2=100K, and R3=10K. The output is 7.4V due to the input current flow through unequal resistor.