It works with double quotes and needed double quotes around the value rollup-type = " 'DELTA' "
... I love the design of this engine, It's a powerful tool for sure.
great job team!!
Problem resolved. So I discovered not all our data sources have identical point names and one of the common points I was using to identify its device name did not exist in certain DS so it reverted to the previous values in the data sources array.
This was nothing to so with the JSON store functionality and its all working as it should now . :) Thanks again guys.