IMPORTANT-Windows-Excel-Info.txt A security feature of the Windows operating system may block running your Excel add-in. To unblock your add-in, run File Explorer, navigate to your add-in XLAM file, right-click the file icon, and choose Properties > General. If you see an Unblock checkbox in the lower-right corner, check the box, and click OK. For detailed instructions, refer to the How-To-Install-Windows-Excel-Addin PDF file.