CComboBoxEx: Make read-only?

How do you make the CComboBoxEx read-only?
I tried the following code in OnInitDoalog, but to no avail:

CEdit* pEdit = (CEdit*)GetDlgItem(IDC_COMBOBOXEX);
pEdit->SetReadOnly(TRUE);

[Don Potts]

You might look at the articles on combo boxes that look up strings in the list portion as you type characters in the edit box. I was browsing through them, and it seems that there's more to getting the edit box than what you are doing.