Php或AS3错误？错误＃2007：参数文本必须为非null

I am new to AS3, and i am trying to do a search type file in php(to pull info that matches a username) and return the result in AS3. The php returns all variables into AS3, except for the first one that enters,when it loops the second time, all variables passes through ok. I am also trying to do a multiple fields search and return the results in AS3 with similar principles but same issue is occurring. Please help me see if it is a php error or AS3 issue.Thanks for your timeI am new to AS3, and i am trying to do a search