back counting updation in Zenon

back counting updation in Zenon

I want to add back counting in Zenon.
Wrote a logic in Control Logix PLC. It is giving me remaining Seconds. For eg. I am executing a time bassed step. This step has to execute for 60 sec. During its execution i am calculating remaining time ( in sec). This remaining time tag is to be displayed in Zenon scada.
In Zenon it is displaying but sometime sciping the seconds like 59,58, directly 56. Not showing 57 on zenon. In PLC it is working correctly.
Reading the remaining tag at highest rate in Zenon. There are no unused tags, error, warning, functions in zenon.