find control in page

Question

HTML

Answer 1

This is probably due to how ASP.NET names the client IDs for nested controls. Look at the page source and see exactly what ASP.NET is naming your control.

For example, looking at my page I can see that the button within the content placeholder renders like this:

In this case FindControl("ctl00$ContentPlaceHolder1$btn1") returns a reference to the Button.