I'm using Custom Lock, and I've stumbled across this problem, I'm using the following command for date
However, it's in lowercase, and I wanted it in uppercase, so I did
However, it showed "$DF(E)$" as a result, and not the date.
You can use the filter of the text and make it uppercase.
By the way, when you use a function like this "tc" with a code inside, you need to erase the quotation marks, because all what you have inside the quotations are printed literal by the other code, because this your output is $DF(E)$.
Other by the way, the output of df(e) is the number of the day in the week, like if the first day of the week in your phone is sunday, the output for df(e) on sunday is 1.