It is very important to verify that you have an up-to-date Microsoft Excel version, if you want XLSTAT to work properly.
There are two ways to update Microsoft Excel.
Updating Microsoft Excel from the Start menu
The first one is to use the Start menu to check for new updates. Click the Start button. There click on All Programs then press the option: Windows Update. Also note that Windows Update is also included in Control Panel.
You will be directed to the Windows update folder. When you have some updates to do you need to allow your computer to install them.
Updating Microsoft Excel from the Microsoft Office website
The second option is to go to the Microsoft Office website and download the Service Pack that corresponds to your version of Office. You will be redirected to the Microsoft Download Center. Click on Download and install the Service Pack.
In both cases, you may need to restart your computer for the update to be taken into account.