Not work for me

Not work for me, i don't know why.
my button toggle:

`<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target=".navbar-ex1-collapse" aria-expanded="false">
					<span class="navbar-toggle-icon">
				      <span class="icon-bar"></span>
				      <span class="icon-bar"></span>
				      <span class="icon-bar"></span>
				    </span>
				</button>`

