Problem with Constraints

Hi, I’m new to blender and I have been working on a model of a person that I want to animate. I’ve modeled him and added the bone structure but I’m having problems with the constraints, the copy location and Ik solver constraint in particular. I’ve added the copy location constraint to the neck targeted to the neckloc but in the constraint box when i fill in the information in the Target OB: box, the information i put in keeps disappearing on me. what am I doing wrong? or what do I do to fix this problem?

When your target is bone , Target OB:Armature and after that BO:bone .
Or maybe some circle-dependences parent-child (look at the terminal messages)?!
Something like:
To bone
add Constraint CopyLocation >Target:box
Attachment or jpeg will make situation more clear.
All the best!