eplex_instance

I would like to be able to refer to more than one eplex instance at a 
time. From the manual, I think I should be doing something like this to 
produce a separate eplex instance:

:-lib(eplex).
:-eplex_instance(mip).

test :-
        mip:(A +B $= 4 ),
        mip:(B $= 3),
        mip:optimize(min(A),Cost),
        writeln(A).

This compiles fine, but on running produces the error:

'calling an undefined procedure mip : (A + B $= 4) in module eclipse'

But replacing mip with eplex in the above example gives the correct 
answer A=1.0. This is using version 5.5 on Win2000 and Solaris 7/8. Am I 
doing something wrong, or is this a bug?

Benjamin Roe,
CPSE, Imperial College