Costs not burdened

 We have some expenditure items that are not cost burdened - I do not know the reason the system generated when they were not burdened - Is there a way to look up the reason ?. these are very old transactions. I tried running them on test system and look at the log file - but it didnt show any reason.

When I try to recalculate the burden cost from the expenditure inquiry screen - the message says " Supplier invoice related to this transaction has been paid and you are using automatic offsets".

How can we determine the reason why these are not burdened.