diff --git a/demo-serving/conf/model_toolkit.prototxt b/demo-serving/conf/model_toolkit.prototxt
index 4fcb909ed8409af0943ee0a495e71b0068f7c040..58f6760b2bbc2b0a6e594c45ce18efc220ac9a34 100644
--- a/demo-serving/conf/model_toolkit.prototxt
+++ b/demo-serving/conf/model_toolkit.prototxt
@@ -28,4 +28,6 @@ engines {
   runtime_thread_num: 0
   batch_infer_size: 0
   enable_batch_align: 0
+  sparse_param_service_type: REMOTE
+  sparse_param_service_table_name: "dict"
 }
diff --git a/demo-serving/op/ctr_prediction_op.cpp b/demo-serving/op/ctr_prediction_op.cpp
index 891288f8509e89657b682500fc2d3331a2ccf7f2..b6fe49642f2c55b569f44d89d5c4085d109d417e 100644
--- a/demo-serving/op/ctr_prediction_op.cpp
+++ b/demo-serving/op/ctr_prediction_op.cpp
@@ -102,42 +102,74 @@ int CTRPredictionOp::inference() {
   predictor::KVManager &kv_manager = predictor::KVManager::instance();
   const predictor::KVInfo *kvinfo =
       kv_manager.get_kv_info(CTR_PREDICTION_MODEL_NAME);
-  if (kvinfo != NULL) {
-    std::string table_name;
-    if (kvinfo->sparse_param_service_type != configure::EngineDesc::NONE) {
-      table_name = kvinfo->sparse_param_service_table_name;
+  if (kvinfo == NULL) {
+    LOG(ERROR) << "Sparse param service info not found for model "
+               << CTR_PREDICTION_MODEL_NAME
+               << ". Maybe forgot to specify sparse_param_service_type and "
+               << "sparse_param_service_table_name in "
+               << "conf/model_toolkit.prototxt";
+    fill_response_with_message(res, -1, "Sparse param service info not found");
+    return 0;
+  }
+
+  std::string table_name;
+  if (kvinfo->sparse_param_service_type != configure::EngineDesc::NONE) {
+    table_name = kvinfo->sparse_param_service_table_name;
+    if (table_name.empty()) {
+      LOG(ERROR) << "sparse_param_service_table_name not specified. "
+                 << "Please specify it in conf/model_toolkit.protxt for model "
+                 << CTR_PREDICTION_MODEL_NAME;
+      fill_response_with_message(
+          res, -1, "sparse_param_service_table_name not specified");
     }
+  }
 
-    if (kvinfo->sparse_param_service_type == configure::EngineDesc::LOCAL) {
-      // Query local KV service
-    } else if (kvinfo->sparse_param_service_type ==
-               configure::EngineDesc::REMOTE) {
-      int ret = cube->seek(table_name, keys, &values);
-      if (ret != 0) {
-        fill_response_with_message(res, -1, "Query cube for embeddings error");
-        LOG(ERROR) << "Query cube for embeddings error";
-        return -1;
-      }
+  if (kvinfo->sparse_param_service_type == configure::EngineDesc::LOCAL) {
+    // Query local KV service
+    LOG(ERROR) << "Local kv service not supported for model "
+               << CTR_PREDICTION_MODEL_NAME;
+
+    fill_response_with_message(
+        res, -1, "Local kv service not supported for this model");
+    return 0;
+  } else if (kvinfo->sparse_param_service_type ==
+             configure::EngineDesc::REMOTE) {
+    int ret = cube->seek(table_name, keys, &values);
+    if (ret != 0) {
+      fill_response_with_message(res, -1, "Query cube for embeddings error");
+      LOG(ERROR) << "Query cube for embeddings error";
+      return 0;
     }
+  }
 
-#if 0
-    for (int i = 0; i < keys.size(); ++i) {
-      std::ostringstream oss;
-      oss << keys[i] << ": ";
-      const char *value = (values[i].buff.data());
-      if (values[i].buff.size() !=
-          sizeof(float) * CTR_PREDICTION_EMBEDDING_SIZE) {
-        LOG(WARNING) << "Key " << keys[i] << " has values less than "
-                     << CTR_PREDICTION_EMBEDDING_SIZE;
-      }
+  if (values.size() != keys.size()) {
+    LOG(ERROR) << "Sparse embeddings not ready; "
+               << "maybe forgot to set sparse_param_service_type and "
+               << "sparse_param_sevice_table_name for "
+               << CTR_PREDICTION_MODEL_NAME
+               << " in conf/model_toolkit.prototxt";
+    fill_response_with_message(
+        res, -1, "Sparse param service not configured properly");
+    return 0;
+  }
 
+  for (int i = 0; i < keys.size(); ++i) {
+    std::ostringstream oss;
+    oss << keys[i] << ": ";
+    const char *value = (values[i].buff.data());
+    if (values[i].buff.size() !=
+        sizeof(float) * CTR_PREDICTION_EMBEDDING_SIZE) {
+      LOG(WARNING) << "Key " << keys[i] << " has values less than "
+                   << CTR_PREDICTION_EMBEDDING_SIZE;
+    }
+
+#if 0
       for (int j = 0; j < values[i].buff.size(); ++j) {
         oss << std::hex << std::uppercase << std::setw(2) << std::setfill('0')
             << (static_cast<int>(value[j]) & 0xff);
       }
 
       LOG(INFO) << oss.str().c_str();
-    }
 #endif
   }