Text in TextBox not detected

Hello im french boy , sorry for my bad english (google traduction is my friend).

The worry is that: the text in the textbox is not detected!

My code is : `if (tb_user.Text == “coucou”)
{
MessageBox.Show(“Sa fonctionne”);
}
if (tb_user.Text == “”)
{
MessageBox.Show(“Sa fonctionne pas putain”);

}`

And the result is : Sa fonctionne pas putain.

(My bunifu textbox is named “tb_user”)

Thanks for you help