# 4. error code 

| code | msg                            |
| -------------- | ------------------------------------------ |
| U1             | merid not found                         |
| U2             | Signature error                            |
| U4             | missing  Parameter                            |
| U5             | invalid  Parameter                            |
| U6             | Orderno repeat                            |
| U7             | Orderno  not exist                            |