Hi Hasila,
Could you please give more details about the issue, looking to the error it seems that you trying to get any tags values from historian using PCo query.
Below are may be the issues
1. Tag doesnot exits or its a wrong Tag
2. For that particular time range values for that tags are not present
3. Historian server's must be running out of memory and hence PCo unable to read values
You can try by giving a long date range with view as "EVENT" if you get multiple values or even a singe value in this time range then it can be concluded that for that specific time values were not present in Historian DB.
Please try this and share the results