EDATE function

Recently, tech support had to do some surgery on my computer, and nothing's been the same since. In excel, the 'EDATE' function no longer works. I'm getting the #NAME? error. I thought at first that I had an error in the formula that I typed, but if hit the 'fx' button on the toolbar to get the list of functions, EDATE isn't listed. Is this related to the version of excel? Any ideas on how to restore this function? Any help would be appreciated. Thanks.