Problem when calling two web services at the same time

I encountered a problem when trying to create a string by calling two different web services that returns a different string. The problem is that I can't seem to 开发者_StackOverflow中文版get both of them, so the WebServiceResult1_string + WebServiceResult2_string result in only the latest appearing.

When make only one web service call, it works. The problem happens when I call two of them.

I'm using ASP.net 4.0 and JQuery. Why can't I get both of the results?