Hi Wilson,
Can you let me know which Little Math software version you're using? You can check the version number by opening Little Math and going to TOOLS > Software Information.
Here are some suggestions in the meantime:
1. Please make sure you have the latest version installed in your computer (v2.1.660). In case you have an older version, we recommend you uninstall your current Little Math first, and then download and install the latest version from your BrillKids Account.
For instructions on how to install Little Math from your account, see:
http://support.brillkids.com/entries/20432326-Installing-and-Setting-Up-Your-Little-Math-from-your-BrillKids-Account-2. Add your Little Math license key to your account by following the instructions here:
http://support.brillkids.com/entries/21333619-How-to-add-a-BrillKids-software-license-key-to-your-BrillKids-Account3. Once you've done Step 1 and 2, please enter your license key again in Little Math, and see if the activation goes through successfully.
If you are still having problems, do write to us at support[at]brillkids[dot]com so we can help you further.