Without looking at an on line parts diagram of the headset in question I'll say that some sort of centering design must exist for the upper cone (the one under the stem) to be stable on the steerer. Some use an "O" ring and tight fit. Others (and IIRC Cane Creek licensed this from Dia Comp) use a conical compression ring and a cone with a matching conical interface. I suspect you're missing this need. Andy.