Dear Friends

I have the following LP problem:

```
cvx_clear;
clear all;
cvx_solver gurobi;
input=[0;2];
M=[20 20];
c=[-1 1];
cvx_begin
variable x(2) nonnegative;
variable y(2) nonnegative;
variable u(2) nonnegative;
dual variable D1;
dual variable D2;
minimize c*y+ M*u
subject to
2*y(1)-u(1)<=12-3*x(1);
y(2)-u(2)<=-18+6*x(2);
D1 : x(1)==input(1);
D2 : x(2)==input(2);
cvx_end
```

When I change solver to the Mosek, I got the following result:

D1=0 D2=-120

and its correct.

When I change solver to the Guobi, I got the following result:

D1=1.5 D2=-120

and its wrong.

When I change solver to the SDPT3 v4.0, I got the following result:

D1=-61.9453 D2=-120

and its wrong.

I think this is a bug!