I am new to openERP and facing issues with HR module.

I have developed mobile application for openERP in Android. Now when I create new leave request, I am getting mail but when I approve or reject any request, I am not getting mail.

I have configured the openERP server for leave_validate as well as leave_refuse. Thats why I got mail when I approve/reject request from server but I am having issue with my app only..

Here is a code to approve a leave request :

    objectParams.add(db_name);
    objectParams.add(user_id);
    objectParams.add(pwd);
    objectParams.add("hr.holidays");
    objectParams.add("holidays_validate");
    objectParams.add(new Integer[]{(Integer) leave_id});

    Object result = client.callEx("execute", objectParams.toArray());

Please help me to sort out this problem. what am I missing..???