[eclipse-users] How to ic:search/6 with symmetry breaking during search (sbds) of lib(ic_sbds)?

Hello ECLiPSe users,

I have some problems with and questions to the sbds method of the search 
predicate of libary ic and the corresponding needed predicate 
sbds_initialise/4 of libary ic_sbds.

http://eclipse.crosscoreop.com/doc/bips/lib/ic_sbds/index.html
http://eclipse.crosscoreop.com/doc/bips/lib/ic_sbds/sbds_initialise-4.html

I followed the N-queens example for setting up symmetry predicates given 
as list to sbds_initialise/4. Here is a simplified version of how I 
tried to build my symmetry predicate:

rotate90(Var,Value,SymVar,SymValue) :-
(
	(not var(Value)) -> (
		Var is SymVar,
		(Value == 'left') ->  SymValue is 'rear' ; true,
		(Value == 'right') ->  SymValue is 'front' ; true,
		(Value == 'front') -> SymValue is 'left' ; true,
		(Value == 'rear') -> SymValue is 'right' ; true
	) ; true
).

In my problem, I am facing a pure value symmetry, at least as far as I 
know and understand it! Thats why "Var is SymVar" and the value is set 
to a symmetrical one. The symmetrical group is the dihedral group, the 
symmetry group of a square. The group elements are: identity, 
rotate90/180/270, reflextionX, reflextionY, flipCorner1, flipCorner2.

However now, search is given my a lot more symmetrical solutions than 
without sbds. I am not sure if the problem are the symmetry predicates 
or there is any conflict/sideeffect with the rest of my code. Am I doing 
or understand something completely wrong?

I would happy to see more examples (of you) or a tutorial of how to 
write symmetry predicates for sbds. Or can anybody of you give me some 
advice or hints?

Thank you for your help!

Best regards,
Martin Berger