dahermit

I am using Windows 7 64-bit computer that comes preloaded with MS Works. Using the MW Works spread sheet I get incorrect data. For instance, using a formula: =SUM(D1-G2) If I had the number 34 in Cell D1 and the number 30 in the cell G2 I should get the number 4 in the cell in which the formula is placed. However, I get the contents of cell G2. What gives? What is causing this. Most of the spread sheet is giving correct answers. Note: could this be caused by opening a spreadsheet constructed by an earlying verson of MW Works in the Current version(9)?