Blank ComboBox initially

My form has a Combo Box [Cb] with DropDownStyle property set to DropDownList.
When the application starts the Combo Box is populated with a Data Table [dt].

Problem resides in the fact that the Combo Box Selected choice [the one that appears] should be blank initially. However when populating it with the Data Table, the first value from the table automatically appears in the combo box.

It should be blank until one of the choices are selected.
Any clues?

This will set the combobox to empty value if this is what you are asking about !

Code:

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Cb.SelectedIndex=-1;

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