GUI

hi
i am developing a program in Visual C using MFC classes.I have a
problem.I have used Listbox to update the user about the status of the
program.For Example
ctlMsg.AddString("Entering Ist Module");
updateData(FALSE);
///perform some operations
ctlMsg.AddString("Entering Second Module");
updateData(FALSE);
..But the problem is that ListBox is not updated before every
operation.For example,list box should show message "Entering Ist
module", before completion of the task.But insteads all these messages
are displayed once my application completes all the task.How can i
counter this problem.Please help me

.