In my spreadsheet which has been produced over many years now, I have two adjacent columns of previous and current energy meter readings, input manually each month, and in the third column I simply subtract the two to obtain a third figure to obtain the usage over that month.


At the end of the year I then sum the third column to give total usage over the year.


Simple really, except that a new problem has just arisen. The Total figure at the bottom of the third column produces a result, but I find that if I change a reading in the second column, whilst the subtraction result changes as expected, the Total figure bizarrely remains unchanged.


I have no idea what has seemingly suddenly caused this, but whatever it is the same is found elsewhere in the spreadsheet where identical calculations are performed.


If I produce a simple table doing the same functions from scratch in an empty part of the spreadsheet, it performs as it should, so I deduce from this that there has been some change to affect the rest of the spreadsheet.


The question is exactly what, and can it be recovered!


Any suggestions gratefully received.


(I tried to copy a part of the spreadsheet to post here, but was unsuccessful. Hopefully the above will suffice.)