sort cards dateTime by field "day" dont works

[Reinhold Venzl-Schubert]

Hi!

I have a stack "work" with 14 cards. Each has a field "day".
I create a new card with the script:

    create cd
    put the short system date into fld "day"

Then I want to sort the card by field "day" with the script

    sort cds of stack "work" dateTime by fld "day"

But I failed. My cards are orderd in this way (content of field "day"):

11.05.09
07.05.09
21.01.09
22.01.09
...
30.01.09
01.02.09
05.05.09

What is my mistake?

Thanks
Reinhold