[Help-glpk] MILP wrong solution

[address@hidden]

  Hi all.

I have a problem solving the MILP problem written in attached file.
I
know that formulation is right, because it was solved with XPRESS
commercial solver without any error or warning. But if I try to solve
it with glpk it does not work. I also tried to change backtrack
routines or some other MILP options, but it still does not wok. Is
there any suggestion you coud give me? Or is it an hard problem for
glpk (even if I don not think so)? 

Thank you for your attention,
Claudio

Economical-1.lp
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