problem with show highway labels in certaint zoom level with mapsforge map

I'm using a mapsforge map ( .map format) in my projet . I want to show highway labels from zoom 13 to zoom 20 .I'm using vetorial map viewer. when i set the minimum zoom to 13 and max zoom to 20 the mapsforge start showing labels from zoom 15 . I use osmarender.xml to symbology and set labels.This is an example of setting the highway labels in my xml file. How can i show labels from zoom 13?

<rule e="way" k="highway" v="trunk"   zoom-max="20" >
                <line stroke="#C7BDBD" stroke-width="4"/>
      <rule e="way" k="*" v="*" zoom-min="13">
                            <pathText k="name" font-style="bold" font-size="10" stroke="#ffffff" />
                            <pathText k="ref" font-style="bold" font-size="12" stroke="#ffffff" fill="#ffffff" stroke-width="2.0" />
                    </rule>
            </rule>