Please note that the expressions in the VDT nodes will return an empty result if any of the values in the expression are empty. Therefore, the result of the VDT in the benefit calculation for the month(i.e. August) will be empty. If you enter an actual value for the month of August for all KPIs linked to the VDT, then you should get a benefit.
An alternative to entering a value would be to set a default value for the KPI nodes in the VDT. So for example, if you edit the node and set the default value to 0 for all the linked KPI nodes, then the benefit calculation will return a result. If the VDT is unable to find a value for the KPI, it will use the default value defined for the node instead. See the screenshot below:
To identify which nodes are returning an empty result in the benefit calculation, you can click on the Description items under the Actuals section. If there are any child items, it will expand to display it's child nodes as per the screenshot below: