LMV601: Hysterisis Fine Tuning

Hello, 

I am using LMV601 as comparator with hysteresis as shown in below. As per calculation It is expected that ,

1. V_out should goes high to 3.3V when , Vin = 21.6V. As at that time Vb = 1.560 > Vref= 1.5V DC. 

2. V_out should goes low to ~0V when , Vin drops to 19.68V.

But practically, Vout is triggering high when Vin is 26V. What can be reasons for it ? even with tuning R2 to 22k1, results is same. Which components can be further tuned ? Also, can I use LM393 comparator inplace of LMV601

Thanks in advance

Prafulla