VS 2005 Checkbox In My Application - Fetch The Data From The Database And Add It To The Dropdownlist Of The Combobox

I have a checkbox in my application,when the checkbox is checked then i want to fetch the data from the database and add it to the dropdownlist of the combobox.Again when the checkbox is unchecked then i want to ramove all the data from the dropdownlist of the combobox.

I did this

Private Sub CheckBox1_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckBox1.Checked = True Then
con = New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=Etech.mdb")

[CODE]...

When the checkbox is checked then the data is added from the database to the dropdownlist of the combobox but when i uncheck it then the data is not removed from the dropdownlist of the combobox. In the above code i think i need to add an else condition to remove the data from the dropdownlist of the combobox and make it empty when the checkbox is unchecked.......but i cant give the proper else condition in the above code.