How can I change my current selected item by either the key or value of my datasource?

I have a Dictionary<uint, string> and a ComboBox using the style DropDownList, where I bind this dictionary, like:

comboBox1.DataSource = new BindingSource(myDic, null);
comboBox1.DisplayMember = "Value";
comboBox1.ValueMember = "Key";

Now I would like to be able to select an arbitrary item of my dictionary with a button click, so given the bound dictionary items:

Dictionary<uint, string> myDic = new Dictionary<uint, string>()
{
    { 270, "Name1" },
    { 1037, "Name2" },
    { 1515, "Name3" },
};

I have tried:

comboBox1.SelectedItem = myDic[270];
comboBox1.SelectedText = myDic[270];
comboBox1.SelectedValue = myDic[270];
comboBox1.SelectedItem = 270;
comboBox1.SelectedValue = 270;

But none of the above changed the selected item.

How can I change my current selected item by either the key or value of my datasource?