This paper establishes the relations between the changes in tho values of the Lagrange multipliers and the changes in the values of tho constraint and objoetivo functions for a non-linear, convex programme based on the classical Lagrangian. Using somo Lagrange multipliers which are larger (smaller) than the optimal ones, it is possible that a point minimizing the Lagrangian is inside the feasible (infeasible) region. Illus-strativo examples are presented for quadratic programming problems.