ClassCastException

Hello, I have problem with PHP SOAP client which calls two web service methods. First method takes as parameter string and returns object of type 'Employee'. Second method takes two parameters of type 'Employee' and returns result of their comparison. Code: 1. $wsdl = new SOAP_WSDL( 'service.wsdl' ); 2. $c = $wsdl->getProxy(); 3. $e0 = $c->getEmployeeByLogin( 'e0' ); 4. $e1 = $c->getEmployeeByLogin( 'e1' ); 5. $c->getComparison( $e0, $e1 ); When I call method "getComparison" (line 5) I get error message: java.lang.IllegalArgumentException: java.lang.ClassCastException@b4d39c I use Axis under Tomcat. I dont understand how to call method "getComparison" with correct parameters. Please help me I cannot find some example which solve my described problem. Thanks in advance Ales