Message=Unable to cast object of type 'System.Windows.Forms.PlaceholderTextBox' to type 'Bunifu.UI.WinForms.BunifuTextBox'

Question

I'm trying to convert a bunifu text into a sender in the key down event

private void TxtName_KeyDown(object sender, KeyEventArgs e)
    {
        BunifuTextBox textBox = (BunifuTextBox)sender;
    } 

but im having this error