How to compare using eval expression and field value pair

I want the table to be generated based on 2 conditions - one condition is comparing eval expression and other field value pair.. how to do that index="myindex" |eval Due_Date_Time = strftime(strptime('Due By',"%d.%m.%Y"),"%d.%m.%Y")|eval now_time=strftime(now(),"%d.%m.%Y")|table ID,Category | where (now_time>=Due_Date_Time) AND ('System Status'!="Completed") This where clause is not working.. please help