使用VBA (excel)在excel 2010中创建一个倒计时计时器

I'm using Excel 2010, and want to create a countdown timer in excel. The code will be started and stopped by using buttons with macros attached to them. The problem occurs when the "start" button is pushed. The code above is utilizing Cell "B1" as the input spot, because I was just trying to get it to work, but every time I tried, it would always say: "Cannot run the macro . The macro may not be available in this workbook or all macros may be disabled". I'm using Excel 2010, and want to create a coun