Hello,

I am facing the following strange problem. I have a simple cost-minimization problem,

```
* Defining in=line comments
$inLineCom # #
Set
i 'type of input' /water, fertilizer, energy, labor, land/;
Variable
Z;
POsitive Variables
X(i);
Equations
cost, con1, con2;
cost.. Z =e= sum(i,X(i));
con1.. X('water')+ X('fertilizer')+X('energy') =e= 2;
con2.. X('water')+ X('fertilizer')+X('energy')+X('land') =g= 2;
Model base /all/;
Solve base min Z using lp;
```

By default, the solver is set to CPLEX and the optimal solution is energy=2. However, if i change the solver, eg

```
Option lp=Xpress;
```

then I obtain a different solution, water=2. The same arises if I set the Xpress optimizer.

Why this happens?

I run GAMS 30.0.3 on windows 10(64bit)