Reading your ost, are you entering actual costs in project as well as your budget cost? If you are only putting in the completion date and marking as complete, project will calculate on your resourcing. If the original was set for 100/day and it actually took 3 days, project will take a value of 100/day to give a total of 300, so its working correctly.
EVA is a comparison of actual against budget cost, so it is usually behind as actual costs are not always calculable immediately the task is complete (in my work, at least).