Datamatrix code problem

[Massimo Linossi]

Hi to all.
I'm using the Daniel "zebra library" and if I print the Qrcode and I test it with this site http://www.onlinebarcodereader.com it is correct.
If I print the Datamatrix code the online reader tells that the code is not correct.
Has someone tried to print Datamatrix codes ?
Thanks a lot.
Massimo