OpenSSL OCSP responder generates OCSP response of unknown status

I created two certificates "rootCA.pem" and "dummy.pem". "Dummy.pem" is signed by "rootCA.pem". Now I want to generate OCSP response. I created index.txt and index.txt.attr files because OpenSSL package did not contain these files.

For OCSP request, I use the following command:

openssl ocsp -no_nonce -CAfile rootCA.pem -issuer rootCA.pem -serial 10153684163450445137 -url http://10.0.2.15:2565 -header Host 10.0.2.15

where serial is the serial number of "dummy.pem".

To run OCSP responder, I used the following command:

openssl ocsp -rsigner rootCA.pem -rkey rootCA.key -CA dummy.pem -index index.txt -port 10.0.2.15:2565 -nrequest 1

where 10.0.2.15 is the IP of my VM (CentOS 7). Both commands executed on same VM.

Index.txt.attr contains unique_subject = no

Index.txt contains V    170820073549Z       10153684163450445137    unknown /CN=aaaabbbbccccdef.com

After expiration date there is an empty TAB for revocation.

The response generated is:

Response verify OK

10153684163450445137: unknown

This Update: Apr 27 12:56:35 2016 GMT

I tried a lot of things but failed. Any kind of help will be highly appreciated.