Struggling to link to a changing pivot

Dear Forum Users,

For many years I have used the Pivot Table to provide results to fairly complex datasets but I am struggling with the tiniest and most basic concept. I have a colleague who wants me to assist him with his expense claims - he is entering information to a table that provides results on a week by week basis and shows categories of use and the gross/net amounts. All well and good so far - the pivots work. My problem came when he wanted to summarise Invoices, Expenses and some other stuff - based on what he entered up til now. Then he added some new categories into his expense sheet and the pivot worked but by extending the pivot, the link to the summary was broken. Hitherto I had been using the =pivots!m$34 to link to the result in the summary but this link is broken when new categories are added at the 'refresh pivot' command. Can anyone explain how I can link a result that appears in the summary sheet to a result in a pivot that can move.

Like I said it is the simplest of tasks but I am flummoxed.

Uncle heFTy