No result return from webservice in one server. Other server can return.

I had an application that consume a webservice and this application is deployed to 2 server (Server A & B).

Server A return empty result. Before that it work ok with result
Server B return result.

No error or exception for Server A.

What will be the problem for Server A not returning any result?

Server A is window server 2000
Server B is window server 2003

Thanks.
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