The error "ERROR: Grouped aggregate function calls may not be nested" could occur during the use of aggregate functions that cannot be nested multiple times or mixing aggregation functions in a *select* that has no *group by* or even the usage of incorrect syntax of functions while creating a aggregate field. In order to resolve this error, I would perform the following checks:
* Check whether the syntax of the functions used while creating a new aggregate field is correct. This can be done by navigating to Help>Functions list menu option or try stating it as a subquery.
* Check the log files available under “<DENODO_HOME>/logs/vdp” folder which helps to debug any errors that occurs in the Denodo Platform.
Hope this helps!