Error when execute SampleEnclave HW mode

After linux-sgx was built according to the tutorial and SampleEnclave HW mode was made, the execution of `./app` met an error "failed to load enclave", then I tried some ways to solve it, including the solution mentioned in this link: [https://www.intel.com/content/www/us/en/support/articles/000057836/software/intel-security-products.html](url)
After that, I tried to remove the folder linux-sgx, and rebuilt it, re-executed SampleEnclave HW mode `./app`, then I met this error:
```
[init ../../../psw/ae/aesm_service/source/core/ipc/UnixCommunicationSocket.cpp:225] Failed to connect to socket /var/run/aesmd/aesm.socket
Error code is 0x4001. Please refer to the "Intel SGX SDK Developer Reference" for more details.
Enter a character before exit ...
```
I didn't find the similar problem as I met, and I wonder how to solve it. HELP! Thanks a lot!