The method insertRecords for tasks associate with leads does not work

The method insertRecords for tasks associate with leads does not work

Hello. good morning.
I want insert a task  with leads in API, but not work and it worked before.
inserted but not associate with Leads, and yes associate well with Contacts.

Example:
It not work :(

<Tasks> <row no="1"> 
<FL val="Subject">Test Task for Leads</FL> 
<FL val="Due Date">2016-04-20</FL>
 <FL val="Status">Deferred</FL> 
<FL val="SEID">635130000009555099</FL>
<FL val="LEADID">635130000009555099</FL> 
<FL val="SEMODULE">Leads</FL> </row> 
</Tasks>  

And it work :)

<Tasks> <row no="1"> 
<FL val="Subject">Test Task for Contacts</FL> 
<FL val="Due Date">2016-04-20</FL>
 <FL val="Status">Deferred</FL> 
<FL val="SEID">635130560010420009</FL>
<FL val="CONTACTID">635130560010420009</FL> 
<FL val="SEMODULE">Contacts</FL> </row> 
</Tasks>  


Why it will be?

Work when you insert a task associate with a lead? 

Thanks.