Rlp error - ethereum_requirements

I have an error please help me, and I did not use Ducker just python
the operating system: Ubuntu

(my_env) hanaa@hanaa:~/cert-issuer$ cert-issuer -c /home/hanaa/cert-issuer/conf.ini
WARNING - Your app is configured to skip the wifi check when the USB is plugged in. Read the documentation to ensure this is what you want, since this is less secure
INFO - This run will try to issue on the ethereum_ropsten chain
Traceback (most recent call last):
File “/home/hanaa/my_env/bin/cert-issuer”, line 11, in
load_entry_point(‘cert-issuer==2.0.15’, ‘console_scripts’, ‘cert-issuer’)()
File “/home/hanaa/my_env/lib/python3.7/site-packages/cert_issuer-2.0.15-py3.7.egg/cert_issuer/main.py”, line 17, in cert_issuer_main
File “/home/hanaa/my_env/lib/python3.7/site-packages/cert_issuer-2.0.15-py3.7.egg/cert_issuer/issue_certificates.py”, line 31, in main
from cert_issuer.blockchain_handlers import ethereum
File “/home/hanaa/my_env/lib/python3.7/site-packages/cert_issuer-2.0.15-py3.7.egg/cert_issuer/blockchain_handlers/ethereum/init.py”, line 9, in
from cert_issuer.blockchain_handlers.ethereum.signer import EthereumSigner
File “/home/hanaa/my_env/lib/python3.7/site-packages/cert_issuer-2.0.15-py3.7.egg/cert_issuer/blockchain_handlers/ethereum/signer.py”, line 1, in
import rlp
ModuleNotFoundError: No module named ‘rlp’

I see you’re running in a virtual environment. make sure you have rlp installed in this environment, and make sure that you’ve ran the cert issuer install for ethereum mode.