makem wroteI needed another client eg. pi and when I came to make this I needed to make another certificate (./build-ca)
You have created a new
root ca which is only
compatible with your new client ..
Roll back all your settings to your original setup if possible .. then create a new cert & key for your new client with (easy-rsa) ../vars & ./build-key client-name
If you cannot restore your original setup then recreate your entire PKI:
http://openvpn.net/index.php/open-source/documentation/howto.html#pki