C# help I do not know where I put the code

Question

Hello, I have 2 textboxes (tbMarcas and tbSubmarcas) Brands and Sub-brands both with autocomplete, but sub-brands need to work first met brands and I do not know how to make it work correctly, there is how I did the code ..


/ / Both operating
private void Auto_marcas (); [...]
private void Auto_submarcas (); [...]


private void Form1_Load (object sender, EventArgs e)
{
CONNECTION.Open ();
Auto_marcas () / / when compiling works 5 stars loads 6000 records in 1sec and makes the autocomplete function
Auto_submarcas () / / this also works but only if compiled tbMarcas with text on it in the textbox, I know it is to be in the load () but do not know where to put it to work, this is my question!
}

---

/ / I've tried this way but does not result


...
private void Auto_marcas (); [...]
private void Auto_submarcas (); [...]


private void Form1_Load (object sender, EventArgs e)
{
CONNECTION.Open ();
Auto_marcas ();


}
private void tbMarcas_Leave (object sender, EventArgs e)
{
Auto_submarcas ();
}
...


How do I solve this problem?