on resolution of a case with KPI it sets my first response and resolve by kpi status to cancelled

Good afternoon am using CRMOL 8.2..2.160 and have created some SLA against a case. the first response sla is set to succeeded when the first response field is set to yes this works, however when i close resolve a case it sets both the resolve and first response kpi records to cancelled. has anybody else had this issue? if i reactivate a case it starts timer again on resolve by. 

why would it set both of them to cancelled if i resolve before the failure time? is it something do with updating a resolved case which is in read only mode should i set it to run on a different status or status reason?

thanks 

Una