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When attempting to select Custom Measurements using Hierarchies in PME 7.2.x and PME 8.0, the following error appears: "An error occurred while attempting to retrieve data"

Issue
An error occurs when selecting Custom Measurements in Hierarchies: "An error occurred while attempting to retrieve data."

Product Line
Power Monitoring Expert (PME) 7.2.x and 8.0

Environment
Reports run from Hierarchy

Cause
An issue occurs with the platform when Custom Measurements are used in conjunction with Hierarchies and Reporting as it produces an error seen below:

Details provided from bFO case #26899801
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ID: 2540356
Timestamp: 1/04/2016 5:04:24.787 PM
Priority: ERROR
Source: ReportView_MultiDeviceUsage
Target: edfe0c00-d1d8-4048-b5d4-d23f541785a2
Category: Reporting View
Computer: APML-EMS
Description: An error occurred while attempting to retrieve data.
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It has been observed that the same report run on the same device and custom measurement can be accessed through “Devices” instead of “Views” in the source selector.

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Steps to reproduce the issue (PME 7.2.2 or 8.0 will do it):
- Generate a device with a custom measurement and data;
- Ensure you can generate a report and see the data (Used Single Device Usage Report);
- Now create a Hierarchy Node based on this new source;
- In the report that worked above, change the source from the device to the Hierarchy Representation;
- You'll now get an error or just 'no data available' depending on the version;

This exception log will state:
PowerMeasurement.Reporting.Processor.ProcessingException: Unexpected error while processing rows. ---> System.NullReferenceException: Object reference not set to an instance of an object. at PowerMeasurement.Reporting.View.Processor.MeasurementMetaDataProcessor.GetMeasurementMetaData(DataRow row) at PowerMeasurement.Reporting.View.Processor.MeasurementMetaDataProcessor.Process(DataRow row) at PowerMeasurement.Reporting.Processor.DataProcessor.ProcessRows(DataTable table, IRowProcessor[] processors)

The Measurement ID from the Reporting prerequisite control is mapped to the Datastore ID to process the measurement meta data. The actual custom measurement does not seem to matter since the code fails to even map to the measurement, let alone gather any data. The issue may be in the platform method 'MeasurementMetaDataProcessor.GetMeasurementMetaData' that maps the measurement selector control ID to the Datastore ID by:
IIdentityMapping measurement = MeasurementIdentityMappings.FindIdentityForDataStoreId(measurementId.ToString());
In here it appears there is a mismatch and the mapping is not found.
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Resolution
This is a known issue in PME 7.2.X and PME 8.0, but has been fixed in PME 8.1 so upgrading is the suggested workaround.