我为啥获取token返回400错误，用户注册都可以？求助~

我参考获取token的文档来写的，获取token；
我的方法：
String content = "{\"grant_type\":\"client_credentials\",\"client_id”:\"YXA6xdoZIANQEeWix1fjFvDbug\",\"client_secret\":\"YXA6mQzq2AZEPPa2d4fZSE5vDr25YP0\"}";
String sr=HttpRequest.sendPost("https://a1.easemob.com/wazert/wazerthnt/token", content);
**.out.println(sr);
返回：
java.io.IOException: Server returned HTTP response code: 400 for URL: https://a1.easemob.com/wazert/wazerthnt/token

at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1305)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:234)
at com.wazert.huanxin.HttpRequest.sendPost(HttpRequest.java:101)
at com.wazert.huanxin.Test.main(Test.java:20)

我确定content中的内容都写好的，都是对的，我今天对了一下午了；
我用的注册：
String user = "{\"username\":\"18667179666\",\"password\":\"18667179666\", \"nickname\":\"zhaozhuo\"}";
String sr=HttpRequest.sendPost("https://a1.easemob.com/wazert/wazerthnt/users", user );
**.out.println(sr);
都是可以的；