I think this may be because you're using NaElement and passing more than one element name/value pair into it. You can do that when issuing the "invoke" call against an NaServer object, but not an NaElement object.
These two should be functionally equivalent (warning, I haven't actually tested this code...):
'You can do that when issuing the "invoke" call against an NaServer object, but not an NaElement object.' Is this only limit in clustered api? If yes, you really answer my question. I asked this question because it works in 7mode api when i run invoke_elem all at one.
my 7mode script:
#not using child_add_string and works.
#here $s is NaServer object.
Anyway, it work for me by using child_add_string and child_add. Thanks for your answer. I will quote this topic as 'resolve' if no other one reply this topic in one week.