[Help-glpk] error with glpsol

[Duilio Foschi]

I am an abolute beginner with GLPK.

I have written the model sample at the end of the MathProg manual ("a
trasportation model") into the file model.mod.

Using GLPSOL version 4.0, I write:

glpsol -m model.mod --simplex --min

and I get the following error message:

reading model section in model.mod
reading data section in model.mod
44 lines were read
generating cost...
generating supply...
model.mod:19:x[New-York,New-York] out of domain
model processing error

I understand that x[New-York,New-York] should not be there at all.

What do I do wrong ?

TIA

Duilio Foschi