clp problem

Hi all,
I handle with constraints logical programing.
If i use constraints, labeling and last one cost function, it find a 
solution (many solutions) with it's cost,
1.constraints 2.labeling 3.cost function (also constraint)

but if i use cost function before labeling --> answer is NO 
1.constraints 2.cost function 3.labeling

if i use minimize instead of labeling --> Found no solution with cost 
-382.0 .. -382.0
1.constraints 2.cost function (also constraint) 3.minimize

any suggestions to solve it ?
:- lib(ic, ic_global, branch_and_bound)
5.8_86

Yours truly
	robert fedus