If you using Windows Vista, there are special procedure you need to do in order to be able to upgrade your version.
Follow the steps carefully as shown below.
Step 1: Set your WinTOTO folder permission.
Navigate to the WinTOTO 2004 or WinTOTO Advance folder and right mouse click on the folder. Select the Properties in the menu.
Switch to the Security tab as shown and click on the "Edit" button.
Select the Users (<Your own user name>-PC\User) follow by ticking the "Full control" "Allow" box. Click "OK" to close the box.
Step 2: Download the upgrade version you are seeking. Make sure you navigate to the download directory and use the WinZip to Extract the contents into a new folder. The best is use the suggested folder by the window as shown.
Open the directory where you have unzipped the files. Double click on the wttupgrade.exe file to run the upgrade. This should be able to allow you to upgrade without any problem.