What could be a solution for this code ? Please help ! This is basic

GAMS Studio
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Variable x1;
Variable x2;
Variable x3;
Variable x4;
Variable z;

Equations
Cons1,
Cons2,
Cons3,
Cons4,
Cons5,
Cons6,
Cons7,
Cons8,
Cons9,

Objective_function;

Cons1.. x1+x2+x3+x4 =e= 1;
Cons2.. x1 =g= 0;
Cons3.. x2 =g= 0;
Cons4.. x3 =g= 0;
Cons5.. x4 =g= 0;
Cons6.. x1 =l= 1;
Cons7.. x2 =l= 1;
Cons8.. x3 =l= 1;
Cons9.. x4 =l= 1;

Objective_function.. (314.159265358-(314.207865x1+314.4346151x2+314.3654865x3+314.5827952x4))(314.159-(314.207865x1+314.4346151x2+314.3654865x3+314.5827952*x4))=e= z
model sample_Example /all/;
options NLP = conopt
solve sample_Example using nlp minimizing z;
Display x1.L, x2.L,x3.L,x4.L, z.L;

I have changed the solver from CONOPT to MOSEK and found the results somewhat acceptable. However, CONOPT tends to give the result as X1=1 and rest of the variable 0.