title: Return null from procedure in MyBatis
body: <p>I can't get the value back from procedure. It does an insert on a table and must return a code. The data is insert correctly, but the code returned is always null.</p>
  
  <pre><code>&lt;parameterMap id="callParameters" type="Call" &gt;
     &lt;parameter property="client" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="originalAnalyst" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="currentAnalyst" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="analystType" jdbcType="INTEGER" mode="IN"/&gt;
     &lt;parameter property="category" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="product" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="process" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="problem" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="priority" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="status" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="serviceType" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="abstract" jdbcType="VARCHAR"  mode="IN" /&gt;
     &lt;parameter property="descript" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="nullField" jdbcType="VARCHAR"  mode="IN"/&gt;
     &lt;parameter property="returnField" jdbcType="VARCHAR"  mode="OUT"/&gt;
     &lt;parameter property="callNumber" jdbcType="VARCHAR"  mode="OUT" /&gt;
     &lt;parameter property="currentDate" jdbcType="TIMESTAMP" mode="IN"  /&gt;
     &lt;parameter property="constant1" jdbcType="INTEGER" mode="IN"/&gt;
     &lt;parameter property="constant0" jdbcType="INTEGER" mode="IN"/&gt;
  &lt;/parameterMap&gt;
  &lt;select id="open-call"  parameterMap="callParameters" resultType="Call"  statementType="CALLABLE"&gt;
     {call ADMAHD30.spr_AutoReq(#{returnField},#{constant1},#{callNumber},#{currentDate},#{client},#{originalAnalyst},#{currentAnalyst},#{analystType},#{category},#{product},#{process},#{problem},#{nullField},#{priority},#{status},#{serviceType},#{abstract},#{descript},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{nullField},#{constant0})}
   &lt;/select&gt;
  </code></pre>
  
  <p>All this attributes are mappend in my object correctly. Is there something wrong?</p>