when I use more than one @DubboReference(mock = "true") tag,only one can use

when I use more than one @DubboReference(mock = "true") tag,only one can use，I have make Mock in correct package
the error is:
`mock error : Failed to create mock implementation class default`
```[DUBBO] Exception when try to invoke mock. Get mock invokers error for service:org.xms.cloud.common.service.WalletRpcService, method:getBalance, will construct a new mock with 'new MockInvoker()'., dubbo version: 2.7.8, current host: 192.168.3.110

org.apache.dubbo.rpc.RpcException: No provider available from registry localhost:9090 for service org.xms.cloud.common.service.WalletRpcService on consumer 192.168.3.110 use dubbo version 2.7.8, please check status of providers(disabled, not registered or in blacklist).```