Null Reference Exception was Unhandled
<p>This is my problem. Been looking around and can't seem to solve it still. The line up to nner exception, is the error itself, and the using system is where my code start. It starts specifically on guestCbox.selectedIndex = dA.guest[dAcurrentEntryShown]; not too sure on how to solve this. </p>

<pre><code>System.NullReferenceException was unhandled
  Message=Object reference not set to an instance of an object.
  Source=WindowsFormsApplication1
  StackTrace:
       at WindowsFormsApplication1.Form1.ShowData() in F:\My Documents\Downloads\WindowsFormsApplication2\WindowsFormsApplication2\WindowsFormsApplication1\Form1.cs:line 127
       at WindowsFormsApplication1.Form1..ctor() in F:\My Documents\Downloads\WindowsFormsApplication2\WindowsFormsApplication2\WindowsFormsApplication1\Form1.cs:line 105
       at WindowsFormsApplication1.Program.Main() in F:\My Documents\Downloads\WindowsFormsApplication2\WindowsFormsApplication2\WindowsFormsApplication1\Program.cs:line 18
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:


    **guestCbox.SelectedIndex = dA.guest[dA.currentEntryShown];
    nightCbox.SelectedIndex = dA.night[dA.currentEntryShown];
    roomNoCbox.SelectedIndex = dA.room[dA.currentEntryShown];
    bfastcBox.SelectedIndex = dA.breakfast[dA.currentEntryShown];**


private void roomCbox_SelectedIndexChanged(object sender, EventArgs e)
{
    if (roomCbox.SelectedIndex == 0)  // if result is Single room
        roomRate = 100;
    else if (roomCbox.SelectedIndex == 1)  // if result is double room
        roomRate = 200;
    else if (roomCbox.SelectedIndex == 2)  // if result is Family room
        roomRate = 300;

    dA.roomType[dA.currentEntryShown] = roomCbox.SelectedIndex;


    CalcPrice();
}


private void CalcPrice()
{

    int price;

    price = roomRate * (guestCbox.SelectedIndex + 1) * (nightCbox.SelectedIndex + 1);

    if (bfastcBox.SelectedIndex == 0) //yes, breakfast
    {
        price = price + 10 * (guestCbox.SelectedIndex + 1);
    }

    priceRoomtxt.Text = "£" + price;


}

private void guestCbox_SelectedIndexChanged(object sender, EventArgs e)
{
    dA.guest[dA.currentEntryShown] = guestCbox.SelectedIndex;

    CalcPrice();
}

private void bfastcBox_SelectedIndexChanged(object sender, EventArgs e)
{
    dA.breakfast[dA.currentEntryShown] = bfastcBox.SelectedIndex;
    CalcPrice();
}

private void roomNoCbox_SelectedIndexChanged(object sender, EventArgs e)
{
    dA.room[dA.currentEntryShown] = roomNoCbox.SelectedIndex;
}


private void nightCbox_SelectedIndexChanged(object sender, EventArgs e)
{
    dA.night[dA.currentEntryShown] = nightCbox.SelectedIndex;
    CalcPrice();
}
</code></pre>
