calculation point quality

[andrew10]

i have a calculation analog point that is showing sub normal current quality. 

IIF( ".Steam Coils" = 0,0,formatval('#',("Server Status.Time.CurrentTime")-(".Steam Coils.CurrentTime")))

the quality of all the points in the expression are 'Good' and i have selected 'Always Good (Ignore Quality of Tags). But i am still getting  'sub normal'.  Any ideas?

[AndrewScott]

If the evaluation of the expression fails and the error action isn't set to "Don't Update" then the quality is set to sub-normal to signify there is a problem. The point's view status shows the last error message, see the "Last Execution" attribute.

[andrew10]

is shows the last execuation was ok

[AndrewScott]

The screenshot shows that the point was last updated on 11th January 2023 (over a month ago) so its likely the quality of the source tags was sub-normal a month ago or it was configured differently back then.

The point not updating may be due to the value not changing significantly. Does the point have a significant change deadband?