vtiger 6.3 webservice“where”子句

Question

I am using the vtiger 6 web service from a while (vtwsclib) ans everything was ok, i moved to a new server,after moving all my queries which contains "where" clause stop working, only queries without conditions are running EX:

$query = "SELECT * FROM ProjectTask   WHERE `projecttaskid`>1";
$query = "SELECT * FROM ProjectTask   WHERE 1";
$records = $client->doQuery($query);

$records is empty in the two cases

$query = "SELECT * FROM ProjectTask ";
$records = $client->doQuery($query);

$records contains 100 records

i can not determine what's the exact problem in my new server which cause this

Notes: - I have no errors, query just returns no results - I stopped the server "mod_security" but nothing changed - All required extensions are installed - Vtiger Application is working fine