Simple topic subscriber callback function not working (C++)

edit

Hey all, I'm trying to get a simple subscriber in roscpp working. I have my node subscribe to a topic with a callback called commandCB. The callback simply prints out that it was called. When I run the code and rostopic info the topic, it says that the node is subscribing to the topic correctly. However, when I publish to the topic, the callback function does not do anything. I rostopic echo the topic and see the message getting published so why wouldn't my callback function simply print out the string? Below is the main part of my code, thank you so much!

https://pastebin.com/ZcyYHCKX

void commandCB(const maxon_slider::maxon_command::ConstPtr& msg)
{
    ROS_INFO("HEARD!");
}

int main(int argc, char **argv)
{
    ros::init(argc, argv, "eric_slider_server");
    ros::NodeHandle nh("~");
    if(!nh.getParam("nodeId",nodeId)){
        ROS_WARN("unable to load required parameter %s!",nh.resolveName("nodeId").c_str());
        return -1;
    }

    std::stringstream sstm;
    std::string res;
    sstm << "/eric_a2z_hand_" << nodeId << "/command";
    res = sstm.str();
    ros::Subscriber command_sub = nh.subscribe(res,10,commandCB);


    ROS_INFO("slider topics started with nodeId=%d",nodeId);

    ros::Rate loop_rate(10.0);
    while (ros::ok())
    {
        ros::spinOnce();
        loop_rate.sleep();
    }
}

Python Code:

import rospy import maxon_slider.msg import maxon_command
pub = rospy.Publisher('/eric_a2z_hand_2/command',maxon_command, queue_size=10)
rospy.init_node('talker',anonymous=True)
msg = maxon_command()
pub.publish(msg)