Filter Tag with with_scope doesne't work

Hi,
i got a problem while trying to filter my blog entries through with_scope. In wagon my filter system it worked quiet well. But when i deploy it to my locomotive site it won't filter these entries anymore.

Here is my Code:

{% assign currenttag = params['tag'] %}
{% with_scope tags: currenttag %}
{% paginate contents.blog by 5 %}
{% for post in paginate.collection %}

              <h5><a href="{{ post._slug }}">{{ post.title }}</a></h5>

              <p>{{ post.text | truncatewords: 50 }}</p>

              <a href="{{ post._slug }}" class="button float-right">Weiterlesen</a>

            </div>
          </div>
        {% endfor %}
        <div class="row content-top-min content-bottom-min">
            <div class="large-12 columns text-center">
                 {% if paginate.previous_page %}
                      <a href="?tag={{currenttag}}&page={{paginate.previous_page}}" class="button arrow">
                            <i class="material-icons">arrow_back</i>
                      </a>
                  {% endif %}
                  {% if paginate.next %}
                       <a href="?tag={{currenttag}}&page={{ paginate.next_page }}" class="button arrow">
                           <i class="material-icons">arrow_forward</i>
                       </a>
                  {% endif %}
              </div>
        </div>
   {% endpaginate %}

{% endwith_scope %}