AMOUNT OF EXAMPLES DOES NOT CORRELATES WITH INPUT DATA LOADED FROM PDFs

on="1.0" encoding="UTF-8"?><process version="8.2.001">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="8.2.001" expanded="true" name="Process">
    <parameter key="logverbosity" value="all"/>
    <process expanded="true">
      <operator activated="true" class="text:process_document_from_file" compatibility="8.1.000" expanded="true" height="82" name="Process Documents from Files" width="90" x="45" y="136">
        <list key="text_directories">
          <parameter key="Forging vs AM" value="C:\Users\xwb15193\Desktop\L.R AM vs F\ScienceDirect\ScienceDirect_articles_04Jul2018_11-57-34.507"/>
        </list>
        <parameter key="add_meta_information" value="false"/>
        <parameter key="keep_text" value="true"/>
        <process expanded="true">
          <operator activated="true" class="text:tokenize" compatibility="8.1.000" expanded="true" height="68" name="Tokenize" width="90" x="112" y="34">
            <parameter key="mode" value="linguistic tokens"/>
          </operator>
          <operator activated="true" class="text:filter_stopwords_english" compatibility="8.1.000" expanded="true" height="68" name="Filter Stopwords (English)" width="90" x="246" y="34"/>
          <connect from_port="document" to_op="Tokenize" to_port="document"/>
          <connect from_op="Tokenize" from_port="document" to_op="Filter Stopwords (English)" to_port="document"/>
          <connect from_op="Filter Stopwords (English)" from_port="document" to_port="document 1"/>
          <portSpacing port="source_document" spacing="0"/>
          <portSpacing port="sink_document 1" spacing="0"/>
          <portSpacing port="sink_document 2" spacing="0"/>
          <description align="center" color="yellow" colored="false" height="105" resized="false" width="180" x="77" y="85">Type your comment</description>
          <description align="center" color="yellow" colored="false" height="105" resized="false" width="180" x="99" y="169">Type your comment</description>
        </process>
      </operator>
      <operator activated="false" class="filter_examples" compatibility="8.2.001" expanded="true" height="103" name="Filter Examples" width="90" x="246" y="289">
        <list key="filters_list">
          <parameter key="filters_entry_key" value="label.contains.and"/>
        </list>
      </operator>
      <connect from_op="Process Documents from Files" from_port="example set" to_port="result 1"/>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
      <portSpacing port="sink_result 2" spacing="0"/>
    </process>
  </operator>
</process>

I tried to tokenize pdf articles, resulting in only 21 examples. Why does it happen? It should outcome many more. To do so, I used: "Process data from files" and inside I included "Tokenize" and "filter stopwords", Which again works but not throughout all the documents. What should I do to fix it?

Cheers,

Antonio