Can't get transforms using waitForTransform

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Hello everyone. I recorded a bag file using messages generated by Stage simulator; thus, when bag file is played, both odometric and scanner messages are sent again. I wrote a function that should receive a laser message and find the associated odometric message, using waitForTransform, on professor's suggestion:

void messageListener::laserCallback(const sensor_msgs::LaserScan msg){
  //std::string frame_id = msg->header.frame_id;
  ros::Time t = msg.header.stamp;
  tf::StampedTransform laserPose;
  std::string error;
  if (listener->waitForTransform ("/odom", "/base_scan", t, ros::Duration(0.5), ros::Duration(0.01), &error)){
    listener->lookupTransform("/odom", "/base_scan", t, laserPose);
    double yaw,pitch,roll;
    tf::Matrix3x3 mat =  laserPose.getBasis();
    mat.getRPY(roll, pitch, yaw);

    pos_node pn;
    pn.x = laserPose.getOrigin().x();
    pn.y = laserPose.getOrigin().y();
    pn.angle = yaw;

    const vector<float>& ranges =  msg.ranges;
    scan_node temp_sn;
    temp_sn.cartesian = polar2cart(ranges, msg.angle_min, msg.angle_increment, msg.range_min, msg.range_max);
    vector<scan_node> tempScanVec;
    tempScanVec.push_back(temp_sn);
    extractCorners(&tempScanVec, 0.1, 0.1, 0.3);
    line2angle(&tempScanVec);

    pn.corn_vec = tempScanVec[0].corners_list;
    nodeInfo.push_back(pn);

   }

  else
    printf("Nothing to do\n");
}

The problem is that the IF block where the trasnform should be found is never executed and I always get the nothing to do printing; this makes me understand that somehow transform is never found. I suppose that problem may regard parameters of the function itself. This is the way I perform subscription:

ros::NodeHandle n;
ros::Subscriber sub_n = n.subscribe("/base_scan", 1000, &messageListener::laserCallback, this);

Does anyone know where I'm mistaking? Thanks