\( A(2,6,2), \; B(-4,0,\lambda), \; C(2,3,-1) \) and \( D(4,5,0) \), \( |\lambda| \le 5 \) are the vertices of a quadrilateral \( ABCD \). If its area is \( 18 \) square units, then \( 5 - 6\lambda \) is equal to ________.