What does the GoodData error Report not computable due to improper metric definition mean?
The error Report not computable due to improper metric definition is most often due to incompatible arrangement of data in your report.
In GoodData, the ability to build reports is dependent on how the various objects interact with each other. In other words, the data model is structured in such a way that certain metrics need other metrics to be used in a report to "communicate" with each other and render correctly.
When the datasets of the metric and attribute used in the report do not connect to each other in the data model, instead of reporting on nonsensical data, GoodData shows an error in the report. For more information about the data model, please check: Building custom reports in Insights.