I have 2 html TR that i make them runat=\"server\" & visible=\"false\" and I have a dropdownlist called citiesDropDownList
If you set visible = "false" on a server control, then the control is not even rendered to the browser. Set display: none instead and then show the control with display: block in your javascript.
Remove the visible=false from the server control as this stops the control being rendered to the page, either set a CSS style with display: none or hide the required controls in javascript.
visible="false" means it doesn't even get rendered into the page, so your selectors aren't finding any elements.
Instead of visible="false" use style="display: none;" to hide the elements, yet still render them in the page.