Simulating Mouse-click on IE Window at specific location

Question

Hello,

I am trying to simulate mouse-click at a particular location on an active Internet Explorer window. Given below is my NUnit test case code. When I run my test case it works perfectly for first time, producing the mouse-click where I want. The next time I run it, it moves the mouse alright but the click does not occur. And when I run it third time it works again and so on. So the mouse-click occurs on every alternate run. Can someone please tell me where is the problem? I want it to work everytime I run the test.

Thanks.

namespace Test
{
using NUnit.Framework;
[TestFixture]
public class SimulateInput
{
    [Test]
    public void TestClick()
    {
        String name = @"C:\5.html - Internet Explorer provided by Dell";
        IntPtr handle = FindWindow("IEFrame", name);  // Get handle

        SetForegroundWindow(handle);  // bring window to front

        Rectangle rect = new Rectangle();  // get window size and location
        GetWindowRect(handle, ref rect);
        rect.Width = rect.Width - rect.X;
        rect.Height = rect.Height - rect.Y;   

        int clickX = rect.X + 18 + (728 / 2);  // set click position
        int clickY = rect.Y + 114 + (90 / 2);                 

        // move mouse to click location
        Cursor.Position = new Point(clickX, clickY);

        // Call API
        int resSendInput;

        INPUT input = new INPUT();
        input.type = INPUT_MOUSE;
        input.mi = new MOUSEINPUT();            
        input.mi.mouseData = 0;
        input.mi.time = 0;
        input.mi.dwExtraInfo = 0;
        input.mi.dx = Cursor.Position.X;
        input.mi.dy = Cursor.Position.Y; 

        input.mi.dwFlags = MOUSEEVENTF_ABSOLUTE + MOUSEEVENTF_LEFTDOWN;
        resSendInput = SendInput(1, ref input, Marshal.SizeOf(input));

        input.mi.dwFlags = MOUSEEVENTF_ABSOLUTE + MOUSEEVENTF_LEFTUP;
        resSendInput = SendInput(1, ref input, Marshal.SizeOf(input));
    }

    public struct INPUT
    {
        public int type;
        public MOUSEINPUT mi;
    }

    public struct MOUSEINPUT
    {
        public int dx;
        public int dy;
        public int mouseData;
        public uint dwFlags;
        public int time;
        public int dwExtraInfo;
    }

    public const uint MOUSEEVENTF_ABSOLUTE = 0x8000;
    public const uint MOUSEEVENTF_LEFTDOWN = 0x0002;
    public const uint MOUSEEVENTF_LEFTUP = 0x0004;

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    [DllImport("USER32.DLL")]
    public static extern bool SetForegroundWindow(IntPtr hWnd);

    [DllImport("User32.dll", SetLastError = true)]
    public static extern int SendInput(int nInputs, ref INPUT pInputs, int cbSize);

    [DllImport("user32.dll")]
    public static extern long GetWindowRect(IntPtr hWnd, ref Rectangle lpRect);
 }
 }