cannot sign a certificates

I'm having issue with the openssl on my edgerouter lite. trying to create certificates for openvpn connection

but i'm stuck at the command ./CA.sh-sign

i got the following error

root@erl1:/usr/lib/ssl/misc# ./CA.sh -sign

Using configuration from /usr/lib/ssl/openssl.cnf

Error opening CA private key ./demoCA/private/cakey.pem

2007172248:error:02001002:system library:fopen:No such file or directory:bss_file.c:398:fopen('./demoCA/private/cakey.pem','r')

2007172248:error:20074002:BIO routines:FILE_CTRL:system lib:bss_file.c:400:

unable to load CA private key

Please help