Issue with trend in VijeoCitect V7.5

I am using VijeoCitect v7.5 on Desktop having Windows-7 OS.
While viewing trends, it is observed that trend is not appearing continuous and value of tag at no. of points shows as "na". The reason behind this issue is still not identified.

It looks like either the connection to the tag has been lost or the value is outside of the range the tag has been configured with. We sometimes see this if a value goes negative when you are expecting 0-100 for example

If all of those values are coming from the same device then I'd check the tag range in tag set up.