You need to call the Bind method:
cbxProjectd.DataBind();
If this is for winforms then you need to make sure what you have is being called, the following works:
BindingSource bs = new BindingSource();
bs.DataSource = new List<string> { "test1", "test2" };
comboBox1.DataSource = bs;
Although you can set the ComboBox's DataSource directly with the list.
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