PCL error in moving least squares

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I am using the Moving Least square code provided in pcl, here is my code exaclty:

<iostream>
<pcl/point_types.h>
<pcl/point_cloud.h>
<pcl/io/pcd_io.h>
<pcl/visualization/pcl_visualizer.h>
<pcl/kdtree/kdtree_flann.h>
<pcl/surface/mls.h>

int main(int argc, char **argv) {
    pcl::PointCloud <pcl::PointXYZ> cloud;
    pcl::io::loadPCDFile("KinectPointCloudChest2_filtered.pcd", cloud); // Create a KD-Tree
    pcl::search::KdTree<pcl::PointXYZ>::Ptr tree(new pcl::search::KdTree <pcl::PointXYZ>); 
    // Output has the PointNormal type in order to store the normals calculated by MLS
    pcl::PointCloud <pcl::PointNormal> mls_points; 
    // Init object (second point type is for the normals, even if unused)
    pcl::MovingLeastSquares <pcl::PointXYZ, pcl::PointNormal> mls;
    mls.setComputeNormals(true); // Set parameters
    mls.setInputCloud(cloud.makeShared());
    mls.setPolynomialFit(true);
    mls.setPolynomialOrder(2);
    mls.setSearchMethod(tree);
    mls.setSearchRadius(0.03); // Reconstruct
    mls.process(mls_points);
    pcl::PointCloud<pcl::PointXYZ>::Ptr mls_cloud(new pcl::PointCloud <pcl::PointXYZ>);
    mls_cloud->resize(mls_points.size());
    for (size_t i = 0; i < mls_points.points.size(); ++i) {
        mls_cloud->points.x = mls_points.points.x; //error
        mls_cloud->points.y = mls_points.points.y;
        //error
        mls_cloud->points.z = mls_points.points.z;
        //error
    }
    pcl::io::savePCDFile("KinectPointCloudChest2_mls.pcd", mls_points);
    return 0;
}

but I get an error throw pcl::IOException ("[pcl::PCDWriter::writeASCII] Input point cloud has no data!"); what to do in this case?