Actual costs after activity has finished (lumped on Data Date)

Hi

I would appreciate some help from any of you guys regarding a issue I am having with spreading actual costs (version 6.2.1)

I have spread a resource (material @ £1/ea) on a WBS Summary Bar that encompasses the activity bars in question however when I look at the actual cost distribution in resource assignment view some of the actual cost has been lumped on the data date (which is roughly a year after the activities had finished)

There are £0 remaining costs (as the scheme has finished)  - I have made sure that planned finish = actual finish and have checked that I haven't stored period actuals in the future by mistake.

How can I get rid of this "future actual" and ensure the entire actual sum is spread over the Actual dates?

I am unable to edit the spread manually as the values are greyed out.

Any help or pointing in the right direction would be much appreciated.

Thanks

Neil