I have found a solution to my problem.

instead of this mdx in the calculated member

measures.Finished

(linkmember([createTime].[hierarchy].currentmember,finishedTime.hierarchy),measures.casecount)

i wrote this

([measures].[casecount],[Createtime].[hierarchy].[all],linkmember([createtime].[hierarchy].currentmember,[finishedtime].[hierarchy]))

That did the trick for me.