Fix the field name "user" -> "userId" in the codeStatus request.
diff --git a/src/mpin_sdk.cpp b/src/mpin_sdk.cpp
index c9a17f6..dcaecbe 100644
--- a/src/mpin_sdk.cpp
+++ b/src/mpin_sdk.cpp
@@ -991,7 +991,7 @@
         util::JsonObject data;
         data["status"] = json::String("user");
         data["wid"] = json::String(accessCode);
-        data["user"] = json::String(user->GetId());
+        data["userId"] = json::String(user->GetId());
         MakeRequest(codeStatusURL, IHttpRequest::POST, data);
     }