Fmincon stopped because the size of the current step is less than the default value of the step size tolerance...How can I solve this?

This is my coding

U=[0.04854 0 0 0; 0.03483 0.03125 0 0; 0.02477 0.02223 0.04000 0; 0.01738 0.01550 0.02807 0.05263];
m=[1.6378; 1.1753; 0.8359; 0.5867];
n=4;

fun=inline('200*0.5.^0.8+1000*0.5.^0.8*x(1).^2+200*0.3.^0.8+1000*0.3.^0.8*x(2).^2+200*0.4.^0.8+1000*0.4.^0.8*x(3).^2+200*0.5.^0.8+1000*0.5.^0.8*x(4).^2');
x0=[1 1 1 1];
a=[5;5;5;5];
b=[200;200;200;200];
A=[-200 0 0 0; 0 -200 0 0; 0 0 -200 0; 0 0 0 -200];

B=inv(U)*(a-m);
LB=[0 0 0 0];
UB=[1 1 1 1];

[x,fval]=fmincon(fun,x0,A,B,[],[],LB,UB,[]);
x;
fval;

L=ones(4,1);
for i=1:n
    L(i)=200*(1-x(i));
end;
L;
L2=U*L+m;

But after running it, it shows

Local minimum possible. Constraints satisfied.

fmincon stopped because the size of the current step is less than
the default value of the step size tolerance and constraints are 
satisfied to within the default value of the constraint tolerance.

<stopping criteria details>

May I ask, how can I solve this?

Answer 1

[Matt J]

There's nothing to solve. It's a good thing.

[Ksss]

Thanks!

[Matt J]

Although, you might try reducing the StepTolerance, if you are not happy with the results.

[Ksss]

I'll try it, thanks again!