Solution: You have to change to the correct value. Right-click on the cell and click Format Cells (or press CTRL+1) and make sure the cell follows the Text format. If the value already contains text, make sure it follows a correct format, for e.g. 22 June 2000. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.