Hi! Anything inside quotes ("") is literal text, a string, so you cannot call functions inside that. In order to do that, you need to use content via the square brackets ([]) as you did for the header. Content allows you to input text, function calls and other markup options like bold or cursive.
Great! Thanks a lot for your prompt reply! All is clear now.
Thank you for having such a nice community and providing such an incredible tool for document writing.