V6.0.6-core- Input-clear-button not working

I’m migrating an app from v5 to v6…
…and in v6 version the <span class="input-clear-button"></span> don’t work now… I don’t know if i’ve anything wrown, I’m not managing any event of the inputs… I don’t know why it’s not working… The code is like the examples, i’ve only change the last slash of the input tag…

            <li class="item-content item-input">
              <div class="item-inner">
                <div class="item-title item-label">User nick</div>
                <div class="item-input-wrap">
                  <input type="text" name="username" id="usua_nick" />
                  <span class="input-clear-button"></span>

Any idea about why it’s not working?
I’ve some forms in the app and no one clears the inputs