Python Openssl Sign and Verify functions - c++

Question

I'm currently working on expanding some python code a co-worker wrote to use X509 certificates with the OpenSSL library. I have managed to get all but a few of the OpenSSL functions working. The libraries / functions that I am using are
from OpenSSL.crypto import FILETYPE_PEM
from OpenSSL.crypto load_certificate, verify, sign, load_privatekey
I am currently creating certificates on my local machine with
openssl req -x509 -newkey rsa:2048 -out rootcert.pem -outform PEM -days 1825
and then "pushing" that to a server (also on local machine), which then returns me a 64 character long random alphanumeric string. I then take the string and sign it using
openssl rsautl -sign -inkey rootprivkey.pem -in string -out signedstring
When I push the signed random string to the server, it takes it to verify (using OpenSSL.crypto.verify) with the certificate I previously sent, the process fails. However, if I use the verify function on the command line (openssl rsautl -verify -inkey rootprivkey.pem -in signedstring), it works.
If I push the private key to the server and use the OpenSSL.crypto.sign (sign(private key, data, digest)) function to sign the same random string and put that into the verify (verify(certificate, signature, data, digest)) function, it works.
I've tried all of the different types of padding when signing the string, and none of those worked. I've also tried doing a digest hash of the string first and then signing that file, based on an old question on SO:
openssl dgst -sha1 -binary < string > digeststring
openssl rsautl -sign -inkey rootprivkey.pem -keyform PEM -in digeststring > signedstring
But obviously that did not work either.
I do not know if I am either generating the certificate and signing the string incorrectly, if I am using the OpenSSL.crypto library incorrectly (I have checked many times to make sure that I am passing the correct variables into the OpenSSL functions), or if the command line functions and the python functions are incompatible.
For reference:
Python 2.7.3
OpenSSL 1.0.1 (March 12)