Resources variance lying in WIP account

A job is cancelled before completion.But when Job was released in 2016, cost of the resource was 0.2937 & for 3859 qty value is 1133. But in 2017 when we return the Resource transaction before cancelling the job, the same resource cost was zero.  So this difference in resource cost stays in WIP account itself. Ideally it should have gone to variance ac right . How to avoid this ?