[eclipse-clp-users] user defined constraints using propia

Hi all,

After studying the Constraint Library Manual I thought that using propia
enables me to turn every prolog goal into a constraint. Using such a
constraint works in general. However it unfortunately doesn't work in
combination with constraint expression connectives like "=>" or "neg".
The use of "neg (my_constraint(X) infers most)" where X is a variable to be
labeled later gives me the following error:
instantiation fault in infers(my_constraint(_518{1 .. 6}), most, _5589{[0,
1]})

Why do I get this error?
And what is the third variable "_5589{[0, 1]" of the infers predicate that
is shown in this error message?

Many thanks for your advice.
Oliver.