diff --git a/index.js b/index.js
index 1a63fbc..c6ee4bd 100644
--- a/index.js
+++ b/index.js
@@ -308,9 +308,11 @@ module.exports = {
     if (backend==='UNICLOUD'){
       const resultCloud = await this.pickupFile2Cloud({mediaType, count, sizeType, sourceType, maxDuration })
       return resultCloud
-    }else // if (backend==='SERVER'){
+    }else if (backend==='SERVER'){
       const resultServer = await this.pickupFile2Server({mediaType, count, sizeType, sourceType, maxDuration, url, header, formData, name})
       return resultServer
+    }else {
+      return { _state: 'CLEINT_FAIL_UNKNOWN_BACKEND_TYPE', backend }
     }
   },