WP Statistics might work on older versions as well, but it is always better to make sure you have updated everything. NOTE: WP Statistics does NOT function on any PHP version that’s older than 5.3).
The GeoIP support also requires a few additional items to function:
the cURL extension for PHP
PHP cannot be running in safe mode
WP Statistics requires a significant amount of RAM for the statistics pages, especially the overview page. Make sure to set your PHP memory limit high enough to support it. While every site has different memory requirements, a reasonable rule of thumb is at least 36 MB, and significantly higher is not unreasonable (128-256 MB).