Have you ever run across the Data Validation box Greyed out in Excel?
The reason Data Validation is Greyed Out is due to the characteristics of your spreadsheet.
If you spreadsheet is “Protected” or being “Shared” with another file, the Data validation tool is turned off in Excel. This is to protect the linked data from producing an error.
Annoying right! In order to fix this issue, make sure you unprotect your worksheet. The other option is to copy the data set into a new worksheet that is not shared. This will allow you to reactivate the data validation tool.