Ccombox mapping in DoDataExchange(CDataExchange* pdx) giving assertion failed

[Beginner_MFC]

I have a CDialog , i decleared the Combobox in .rc file , i can see that combobox on screen but as soon as i do DDX mapping of this combobox , dialog dont open and produces asseetion failed. I have added other combobox in same dialog but addidtion of this combobox produces above mentioned problem.Sample code are below:

// Mydialog.h
CComboBox  combo_one ;
CComboBox  combo_two;
CComboBox  combo_three;
CComboBox  combo_four;

//MyDialog.cpp

void MyDialog :: DoDataExchange(CDataExchange* pDX)
{
DDX_Control(pDX, IDC_COMBO_ONE, combo_one);
DDX_Control(pDX, IDC_COMBO_TWO, combo_two);
DDX_Control(pDX, IDC_COMBO_THREE, combo_three);
DDX_Control(pDX, IDC_COMBO_FOUR, combo_four);
}

//Mydialog.rc

COMBOBOX   IDC_COMBO_ONE, 10.,20,30,40, CBS_DROPDOWN
COMBOBOX   IDC_COMBO_TWO, 20.,30,30,40, CBS_DROPDOWN
COMBOBOX   IDC_COMBO_THREE, 30.,40,30,40, CBS_DROPDOWN
COMBOBOX   IDC_COMBO_FOUR,40,50,30,40, CBS_DROPDOWN

i am getting no error when i added and mapped IDC_COMBO_ONE, IDC_COMBO_TWO,IDC_COMBO_THREE but as soon as i mapped IDC_COMBO_FOUR in DoDataExchange , error of assertion failed comes.
I debugged and found that when i hover combo_four variable during debug its hwnd is null while other three varaible have some memory.

[Arjay]

What is tue resource ID of IDC_COMBO_FOUR ? Does it conflict with other resource IDs?

[VictorN]

... as soon as i mapped MBO_FOUR in DoDataExchange , error of assertion failed comes.
I debugged and found that when i hover combo_four variable during debug its hwnd is null while other three varaible have some memory.

Where exactly "assertion failed" happens?

[Beginner_MFC]

No its unique it doesn't conflict with other resource id.

[Beginner_MFC]

It fails at line DDX_CONTROL(pDX, IDC_COMBO_FOUR, combo_four.

[VictorN]

Is the IDC_COMBO_FOUR associated with a combobox?
Does this combobox belong to your dialog?

[Beginner_MFC]

Yes it belongs to combobox and combobox belongs to MyDialog

[VictorN]

Could you post your project? (in .zip archive, without debug. release, .vs folders)

[VictorN]

error of assertion failed comes.

What text (exactly!) do you see?

I debugged and found that when i hover combo_four variable during debug its hwnd is null while other three varaible have some memory.

Sure it is NULL! just because this control has not been subclassed yet!

So how about sending the test project?