Grand Total come out different than the sum

Hi All,

I browsed a cube and the grand total is different from the sum of the all the rows displayed.  Because I created this project from my mock-up database, I know the raw data well.  The figures are all positive, but the total is negative.  Why is that and how do I fix it?  

Also, is there a way to modify the Grand Total row such as changing the header or remove the total?

BI Analyst