error for computing explicit MPC controller in matlab 2013a

i am currently use matlab 2013a, and i am doing computation on system quadruple-tank with Explicit MPC, when i use the sintaks from matlab, only error happen, and matlab said that :

Error using mpc (line 156) The field "ScaleFactor" in structure "ManipulatedVariables(1)" is invalid.

Error in skripsi1_deskripsisistem (line 62) mpcobj=mpc(Hk,Tp,p,m,Weights,MV,OV);

please if anyone can answer that problem, i need your help