I can not see LEADID in tasks of API

I can not see LEADID in tasks of API

https://crm.zoho.com/crm/private/xml/Tasks/getRecordById?authtoken=[authtoken]&scope=crmapi&id=615130000010740347


R=
<response uri="/crm/private/xml/Tasks/getRecordById">
<result>
<Tasks>
<row no="1">
<FL val="ACTIVITYID"> 615130000010740347</FL>
<FL val="SMOWNERID"> 639130000001901075 </FL>
<FL val="Task Owner">
<![CDATA[ Gabino ]]>
</FL>
<FL val="Subject">
<![CDATA[
RELATION
]]>
</FL>
<FL val="Due Date">
<![CDATA[ 2016-06-25 ]]>
</FL>
<FL val="Status">
<![CDATA[ No iniciado ]]>
</FL>
<FL val="Priority">
<![CDATA[ Normal ]]>
</FL>
<FL val="SMCREATORID"> 639130000001901075</FL>
<FL val="Created By">
<![CDATA[ Gabino]]>
</FL>
<FL val="MODIFIEDBY">639130000001901075</FL>
<FL val="Modified By">
<![CDATA[ Gabino]]>
</FL>
<FL val="Created Time">
<![CDATA[ 2016-05-25 13:18:05 ]]>
</FL>
<FL val="Modified Time">
<![CDATA[ 2016-05-25 13:18:05 ]]>
</FL>

</row>
</Tasks>
</result>
</response>

I cant see the field LEADID  and it is associate with a Lead.

Why it will be?

Thanks