Many people facing this issue, the flash stats graph not displaying. I think I found the root cause and solution.
The root cause might be the allocated memory size not enough for this plugin, which is 32 MB only by default.
You may found that there is an error log file under wp-admin folder. Try to open it with Notepad, and if you see this line:
"PHP Fatal error: Allowed memory size of 33554432 bytes exhausted ...)"
it means that allocated memory size for your wordpress only 32MB.
Increase the allowed memory size to 64MB.
Edit wp-config.php and enter the following line:
It works for me. Hope for you too. Good Luck.
My blog: http://www.mauhorng.com/blog/