Hi,
I believe that you need to convert the numerical output of your date functions into strings. Try preceding each expression with CHAR (). Of note, you may also use the FORMAT () function to create strings with the right number of digits and decimals.
Char (Year( :Date )) || " - " || Char (Week Of Year( :Date ))
// or
Format (Year (:Date), "Fixed Dec", 4, 0) || " - " || Format (Week of Year (:Date), "Fixed Dec", 2, 0)
Best,
TS
Thierry R. Sornasse