หนู inner join 3 ตารางไม่ได้ค่ะ รบกวนผู้รู้ช่วยดูโค๊ดให้ด้วยนะคะ

	$strSQL = "SELECT employee.idcard , employee.name , employee.office , office.id , office.office_name , income.idcard , income.date FROM employee inner join office on employee.office = office.id inner join income on employee.idcard = income.idcard WHERE (month(income.date) LIKE '%".$sel_month."%' AND name LIKE '%".$_GET["txtKeyword"]."%')";