Workflow Report

Hello

I am attempting to send out multiple reports to multiple groups in the same scheduled work flow. The error message I receive on all 5 reports being sent is as follows:

Report generation procedure for report '5 Year Retail Petroleum Project Plan - Calgary' failed due to internal error.
Organization: Federated Cooperatives Limited
Triggered by User: Kevin Mack
Scheduled Workflow Rule: Region Petroleum 5 Year Project Plan

I have a feeling this may be due to one of the fields that needs to be defined before the report is generated. This field asks the user to select which years to draw the data from. The field I am thinking of is listed as follows in the workflow:

Execute on behalf of <Planned Year for Construction> is in {'2015'}{'2016'}{'2017'}{'2018'}{'2019'}

I am wondering if I have this set up correctly.

Any help on this would be greatly appreciated.