I have Versions 4.2, 4.3, and 5.1 of Enterprise Guide on my machine. In 4.2, the Conditional Highlighting add-in works great. In 4.3 and 5.1 I receive the same error message as you. If you go to the "About" tab on the link above, you will see This sample includes a downloadable custom add-in task that can be used in SAS Enterprise Guide 4.2 only. You can use the task to create reports with conditional highlighting, also known as trafficlighting. I suspect that you are using a newer version of EG...
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