Are you seeing the following login screen?
DecisionPoint for Excel, looks as though you are seeing the wrong authentication screen when launching the Designer application. Please can you select properties on the installer which you download or on DPD.exe within the program files and confirm this is Product Version is 126.96.36.1995 or above.
If not you will need to uninstall the version you currently have and download the latest from http://www.antivia.com/decisionpoint-excel/download_xl.php
Once you are sure you have the latest version of the product. Please can you add the attached .decisionpoint.key file from the attached zip to your user folder on the machine in which you have DecisionPoint Designer installed and then re-launch the application. For example C:\Users\drichardson (I have attached a video). Please also delete the "antivia" folder from user folder prior to launching DecisionPoint Designer.