In some cases you may see incorrect output information with your merge fields or place holders because you are entering a URL Encoded field name.
Example: «Employee%5Fx003a%5FLast%5Fx0020%5FName»
Use the following tool to decode the field name: http://meyerweb.com/eric/tools/dencoder/
The actual SharePoint list column internal name is ‘Employee_x003a_Last_x0020_Name’
You can also see the actual internal name on hover of the field from list settings in your browsers status area.
View ‘SharePoint Document Merge List Column Name Checker’ PDF with screenshots