How do I track down where this error is coming from? Without a Point ID, I am at a loss if it is an excel or processbook thing (which are the two ways we currently access data). But I see these kinds of errors a lot.
From first glance it appears that this message could be from ProcessBook's Calculation Data Set since the PointID=0. To verify this, can you check the Network Manager Statistics in SMT and check if the Connection ID in the error message is from ProcessBook?
According to your error, this kb should help https://techsupport.osisoft.com/Troubleshooting/KB/KB01521/
In KB provided above by Ricky, there is a Performance equation test 'pipetest' tool. It will check on your syntax and its test results.
But if you have a AF client installed? I would normally go in to my test database and see if any PE syntax works or not. There are very minor difference between the two and AF Client gives you the GUI help menu which is also nice.
Retrieving data ...