Hi,
if you change the string into
st := '24'#0'12'#0'09';
Then it will work, if you are going to parse the string first then ditch the #0 and use something useful, (like adjust it to something working '24/12/09')
Also this is more like a bug or short coming in the
RTL since ages, as it is enforce the need for separator even with #0.
Could be fixed in newer versions ! as not working on my XE8.