I am currently running Nav 2009 and have a maintenance contract with 20 objects attached to it (previously invoiced for the last year) which has now decided to glitch. When creating the service invoice for the new month the invoice will only select 9 of the objects. 

I have removed and re-added each line and re-calculated the lines to see if this would rectify the problem but it has not worked. Does anyone have any ideas as to why this is not selecting all 20 objects?