Problem to create a task related with lead

I'm using the zohocrm php sdk for API v2, I try create a tasks with a lead.I'm using the zohocrm php sdk for API v2.

I tried to create a task with a lead

This is the code:

Owner' => 'ID',

'Subject' => 'asunto',

'$se_module' => 'LEADS',

'Who_Id' => 'LEAD ID,

'Status' => 'En progreso',

'Solicitante' => 'Email',

'Coordinador_del_solicitante' => 'email',

'Coordinador_del_due_o_de_la_persona' => 'email',

'Gerente' => 'email',

'Priority' => 'Alta',

'Description' => 'description',

'Send_Notification_Email' => true,

when i try to create a task with an contact this code works, but when i try to create a task I change the field Who_Id for What_Id and the creation works but have no relation with a lead.