hi Bruce
Thanks a lot for your kindly help 
the example helped me to revel the secret. a document setting is affecting the behavior. Form properties -> Defaults -> Choose target version, it is set to 9.1+ in your sample XDP, but set to 10+ by default in mine.
this perfectly solved my case, and I surely could not find this secret without your help
Thanks again:) wish you a good day.
Regards
Wu, Xin
