diff --git a/broker/src/main/java/com/xiaoleilu/loServer/action/admin/AdminAction.java b/broker/src/main/java/com/xiaoleilu/loServer/action/admin/AdminAction.java
index 8e4aebf4..4f84956a 100644
--- a/broker/src/main/java/com/xiaoleilu/loServer/action/admin/AdminAction.java
+++ b/broker/src/main/java/com/xiaoleilu/loServer/action/admin/AdminAction.java
@@ -46,17 +46,18 @@ abstract public class AdminAction extends Action {
         }
         
         String nonce = request.getHeader("nonce");
-        if (!StringUtil.isNullOrEmpty(nonce)) {
+        if (StringUtil.isNullOrEmpty(nonce)) {
             nonce = request.getHeader("Nonce");
         }
         String timestamp = request.getHeader("timestamp");
-        if (!StringUtil.isNullOrEmpty(timestamp)) {
+        if (StringUtil.isNullOrEmpty(timestamp)) {
             timestamp = request.getHeader("Timestamp");
         }
         String sign = request.getHeader("sign");
-        if (!StringUtil.isNullOrEmpty(sign)) {
+        if (StringUtil.isNullOrEmpty(sign)) {
             sign = request.getHeader("Sign");
         }
+        
         if (StringUtil.isNullOrEmpty(nonce) || StringUtil.isNullOrEmpty(timestamp) || StringUtil.isNullOrEmpty(sign)) {
             return ErrorCode.INVALID_PARAMETER;
         }
diff --git a/broker/src/main/java/com/xiaoleilu/loServer/action/channel/ChannelAction.java b/broker/src/main/java/com/xiaoleilu/loServer/action/channel/ChannelAction.java
index 8c9bfa6d..2d8771b9 100644
--- a/broker/src/main/java/com/xiaoleilu/loServer/action/channel/ChannelAction.java
+++ b/broker/src/main/java/com/xiaoleilu/loServer/action/channel/ChannelAction.java
@@ -34,19 +34,19 @@ abstract public class ChannelAction extends Action {
     @Override
     public ErrorCode preAction(Request request, Response response) {
         String nonce = request.getHeader("nonce");
-        if (!StringUtil.isNullOrEmpty(nonce)) {
+        if (StringUtil.isNullOrEmpty(nonce)) {
             nonce = request.getHeader("Nonce");
         }
         String timestamp = request.getHeader("timestamp");
-        if (!StringUtil.isNullOrEmpty(timestamp)) {
+        if (StringUtil.isNullOrEmpty(timestamp)) {
             timestamp = request.getHeader("Timestamp");
         }
         String sign = request.getHeader("sign");
-        if (!StringUtil.isNullOrEmpty(sign)) {
+        if (StringUtil.isNullOrEmpty(sign)) {
             sign = request.getHeader("Sign");
         }
         String cid = request.getHeader("cid");
-        if (!StringUtil.isNullOrEmpty(cid)) {
+        if (StringUtil.isNullOrEmpty(cid)) {
             cid = request.getHeader("Cid");
         }
 
diff --git a/broker/src/main/java/com/xiaoleilu/loServer/action/robot/RobotAction.java b/broker/src/main/java/com/xiaoleilu/loServer/action/robot/RobotAction.java
index 399513c1..a619af82 100644
--- a/broker/src/main/java/com/xiaoleilu/loServer/action/robot/RobotAction.java
+++ b/broker/src/main/java/com/xiaoleilu/loServer/action/robot/RobotAction.java
@@ -38,21 +38,22 @@ abstract public class RobotAction extends Action {
     @Override
     public ErrorCode preAction(Request request, Response response) {
         String nonce = request.getHeader("nonce");
-        if (!StringUtil.isNullOrEmpty(nonce)) {
+        if (StringUtil.isNullOrEmpty(nonce)) {
             nonce = request.getHeader("Nonce");
         }
         String timestamp = request.getHeader("timestamp");
-        if (!StringUtil.isNullOrEmpty(timestamp)) {
+        if (StringUtil.isNullOrEmpty(timestamp)) {
             timestamp = request.getHeader("Timestamp");
         }
         String sign = request.getHeader("sign");
-        if (!StringUtil.isNullOrEmpty(sign)) {
+        if (StringUtil.isNullOrEmpty(sign)) {
             sign = request.getHeader("Sign");
         }
         String rid = request.getHeader("rid");
-        if (!StringUtil.isNullOrEmpty(rid)) {
+        if (StringUtil.isNullOrEmpty(rid)) {
             rid = request.getHeader("Rid");
         }
+
         if (StringUtil.isNullOrEmpty(nonce) || StringUtil.isNullOrEmpty(timestamp) || StringUtil.isNullOrEmpty(sign) || StringUtil.isNullOrEmpty(rid)) {
             return ErrorCode.INVALID_PARAMETER;
         }