Mxsetpr problem in c#

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C#3.5

MatLab

I am using the code from a book to convert a double vector to an mxArray mxPointer
the code is as follows.
but it gives "assertion failed" error on the line of

mxSetPr(mxPointerBuffer, mxPointerTemp);

fhs pointer passed to vector_check is invalid and does not appear to have come from any of the following routines: vector_malloc, vector_calloc, vector_realloc maxMaloc*.mxCalloc*, mxRealloc*...

but the two lines of

mxPointerTemp = Marshal.AllocHGlobal(dbVector.Length * Marshal.SizeOf(dbVector[0]));
            Marshal.Copy(dbVector, 0, mxPointerTemp, dbVector.Length);

have done this tasks, right?
it seems before I run it on 32bit Matlab without problem, now it runs on 64bit Matlab and the problems come out.
I could not find a way to solve this problem.
Any one give a hint?
thanks!!

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Collections;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication2
{

    public partial class Form1 : Form
    {

        [DllImport("libmx.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr mxCreateDoubleMatrix(int m, int n, mxComplexity flag);

        public enum mxComplexity
        { mxREAL, mxCOMPLEX };

        [DllImport("libmx.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern void mxSetPr(IntPtr pa, IntPtr preal);

        [DllImport("libmx.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr mxDuplicateArray(IntPtr pa);

        [DllImport("libmx.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr mxCreateCharArray(int pa, int[] dim);		


        public Form1()
        {
            InitializeComponent();

            
            double[] db_A = { 1.1, 2.2, 3.3 };
            IntPtr mx_A = (IntPtr)null;
            mx_A = double2mxArray_vectorRowReal(db_A);

        }

        public static IntPtr double2mxArray_vectorRowReal(double[] dbVector)
        {
            // convert a double vector to an mxArray mxPointer 
            // transfer to an mxArray vector with number of row = 1

            int vectorSize;
            vectorSize = dbVector.GetUpperBound(0) - dbVector.GetLowerBound(0) + 1;

            IntPtr mxPointer = (IntPtr)0;
            IntPtr mxPointerBuffer = (IntPtr)0;
            IntPtr mxPointerTemp;

            int col = vectorSize;
            double[] dbVectorBuffer;
            dbVectorBuffer = new double[col];

            try
            {
                mxPointerBuffer = mxCreateDoubleMatrix(1, col, mxComplexity.mxREAL);
            }
            catch
            {
                System.Console.Write("We cannot create a pointer mxArray. Please check again.");
                return (IntPtr)0;
            }

            mxPointerTemp = Marshal.AllocHGlobal(dbVector.Length * Marshal.SizeOf(dbVector[0]));
            Marshal.Copy(dbVector, 0, mxPointerTemp, dbVector.Length);

            mxSetPr(mxPointerBuffer, mxPointerTemp);

            mxPointer = mxDuplicateArray(mxPointerBuffer);
            Marshal.FreeHGlobal(mxPointerTemp);

            return mxPointer;

        }
    }
}

What I have tried:

I have debugged step by step and check the pointer and it seems nothing is null, or rempty. the poiter has been assigned with a memory.