You might be seeing the error message when you try to open a Excel work paper in Engagement.

Workaround:

1. Close all Excel papers, and open a blank Excel file outside of Engagement.
2. Click the Microsoft Office Button on the top left , click Excel Options, and then click Add-Ins.
3. Click Manage drop-down list, select disabled item, and click Go.
4. Select all items in the disabled dialog box and click Enable.
5. Close Excel Options then try to open Excel files in Engagement again.