Convert text to date

I am at a loss as to why my Toolbox expressions don’t appear to evaluate when used in text or input boxes. I cannot get a text box to display the current users name from an expression. When are expressions evaluated?
I have read the examples on Toolbox, and can see no differences. I am not currently on a plan (waiting to finish app) - is that perhaps a reason?

Error message received.

Input box for date

Expression to evaluate date